Testimonials

KW500 + PSU & KW25 DAC

Earlier this year having read many forums and reviews (and also having heard a friend’s non-upgraded A5, I took a gamble and acquired a KW 25 CD, a KW 25 DAC, KW500 & associated PSU for sale on ebay.

Set it all up, using our own branded cables (interconnects/balanced cables/toslink/speaker cables and power cables) driving a pair of Kralk 30/4 speakers. Power cables all plug in via a PSM 1512 Puritan block.

The DAC had already had a stage 1 upgrade, completed by John a year or so before I bought it.

The system sounded great, but sadly the DAC Toslink input was damaged in that it would not grip the toslink cable as securely as it should. I looked around and did some research on JS Audio and John – one of, if not the, leading specialist in servicing, repairing and upgrading Mus Fid (as well as other brands of high end) equipment.

Having read the testimonials and knowing the results we have had on a personal level, where we have carried out service/repair/upgrades to vintage speakers along with the odd tweak to more straightforward amps, I telephoned and spoke with John about his work, the different upgrades and what each entailed.

John was happy to advise and discuss what the main benefits would be of having the KW500 & PSU upgraded. The repair to the DAC toslink input was not a big job, but is often something that requires repair at some stage, being a common weakness of that unit.

Having discussed things with John, including timescales etc. for the work to be carried out, I decided to go ahead and have the stage 2 upgrade to the amp and PSA alongside the toslink repair. I am so glad that I had the conviction to do so. No regrets whatsoever and money very well spent.

It also made sense to me in that, given that the equipment was pushing towards 20 years old, no doubt many existing parts were probably getting tired. A complete overhaul would also, more than likely, set the equipment up for another 20 years.

On its return I plugged everything back in I let it play for 5 or 6 hours before sitting down for a listen.

However, first impressions were not what I had hoped and were underwhelming to say the least. But, knowing what I know, I put another 20 – 30 hours or so of airtime into it and then sat down and listened to it again.

The results were beginning to show through:- more clarity and separation, deeper sound stage, hidden background vocals coming to the fore, instruments more lifelike and with better placement in the overall soundstage, whilst the bass carried good weight, but at the same time was articulate and detailed without overpowering or drowning out the wonderful mids and articulate sweet top end. All this being delivered quite effortlessly.

An improvement across the board in terms of performance and overall sound. £20,000 on new speakers and an amp would not necessarily have provided the improvements I was now enjoying across many different genres, Black Sabbath, Kiss, Adele, Ed Sheeran, Rag ‘n’ Bone Man, Lady Gaga, Paloma Faith, Eva Cassidy, Stevie Ray Vaughan Ami Winehoue, Diana Krall, Royal Philharmonic to name but a few.

For anyone in a similar situation I can only advise that a stage 2 upgrade, with John, is very well worth the effort, both financially and sonically, and is, in all honesty, a no-brainer. It takes you to a whole new level in terms of music pleasure, no matter what the source.

There was minor problem with the power side, on one of the protection relay circuits (I think it was) but John quickly sorted this minor niggle out. It did not actually stop me from using the system, it just meant having to turn my DAC off and on again to effectively by pass the relay circuit.

Another 50 hours or so of play time and things have improved further. Drums and bass guitar become more vivid in the overall soundstage but remain crisp and controlled without impacting the mid and high end. An example is Adele 25 album, it is as if she is singing right in front of you with her band just sat behind her on the stage – your own real life concert – wow!!.

John a big thank you for your time, patience and skill. I will certainly be advising customers to consider upgrading their existing equipment and I am certain I will be sending equipment down to you in the future.

Rating 11 out of 10 !!

I purchased a 23 year old MF Nu Vista m3 amplifier, which hadn’t been used for 12 years due to unforeseen circumstances by the previous owner.
Once I connected the amplifier up and after a few days, I could clearly hear that there was a fault with the left channel.
On doing alittle research on Google I came across JS Audio’s website and made contact with John, after a detailed conversation we agreed the best solution would be a stage 2 upgrade.

After collecting my amp as scheduled, and have been listening for the past 7 weeks now I can truly say the sound is immersive, clear and 3 dimensional.

Johns knowledge and service can’t be recommended enough.

Thank you

After hearing a demo at a Hifi show I bought a preowned MF A5 amp about 12 years ago. Since then I have been very happy with the amp which has performed flawlessly. Then, very recently, when I switched on the amp, there was a bang, accompanied by a burning smell. My first thought was that an Electrolytic capacitor had blown up. Took off the lid of the amp, all capacitors ( about a dozen) looked ok and I could not see any damage. So I did an internet search and found JS Audio Repairs, a company which specialises in MF equipment repairs. My phone call was answered by John Sampson. He immediately diagnosed the problem as a faulty mains switch. He quoted me a reasonable repair cost. In our discussion he also advised me that he could offer an amplifier upgrade service. In consideration of the age of the ampl, the number of Electrolytic Capacitors, and the sound enhancement which John stated the upgrade would produce, I decided to go ahead. John quoted a 3 to 4 week lead time. The amp was returned exactly within the quoted lead time. Having done some listening tests, playing a number of different albums, what a superb improvement in the sound ! The soundstage is now wider, more open. There is more clarity, detail, and depth in the audio. The bass frequencies e.g drums, are really great, more pronounced and punchy . I love the improvement in the sonic/audio performance . It is definitely worth the investment in the upgrade work. In relation to John personally,I chatted with him a few times and really enjoyed our telephone conversations. He is very personable, genuine, and knowledgeable, particularly as he worked at Musical Fidelity for many years . He is also a very interesting person to talk with
I unhesitatingly recommend his services!

Upgrade to my aging MF B1 – was getting to sound quite dull after many years (probably since 1992/3 around that time when I bought it new). Upgrade of components by JS Audio a few weeks ago. Now sounds incredible! Never heard such clarity and depth before from this amp. Much appreciated. Massive thank you!

This amplifier is now about 20 years old. I’ve owned it for the last 12 years. it was beginning to develop problems on the volume control at low volumes. It also had a bit of an issue with the selection dial. I realised I might experience a more serious issue near future and so I did some research and gave John a phone. He clearly explained to me the reasons for the problems that I was experiencing and their solutions. I opted to take the upgrade route because that was the most cost-effective solution for me. Basically a ‘no brainer’.
I am writing this about six weeks after its return and these are my reflections. Everything is better. I did not realise that an upgrade in the amplification would have such a profound effect on the quality of sound across the board.
The most exciting element has been the improvement in PRaT (Herb Reichert). For some tracks that I have played, I have not been able to stop myself from getting up and dancing. (Specifically Ian Dury’s ‘Sweet Jean Vincent’ was the first.)
Clarity has improved across the board. The sound stage with each instrument given its own space is wondrous. In particular, the tone and presentation of certain instruments, which were already great in my musical fidelity universe, has gained even more presence and fidelity. (Witness the saxophone at 2 mins 56 secs in John Martyn’s ‘Solid Air’.)
Lower down the register drums and bass guitar become more controlled and given greater emphasis which is nowhere more apparent than the opening bars of ‘Watching the Detectives’ by Elvis Costello- never so startling, immediate or well-defined.
Obviously, all of this will continue to improve. I cannot speak too highly of the transformation John has achieved and the pleasure that my revitalised amplifier has given me. It is worth way beyond the monies that I’ve invested.

My ticker gave out and I just couldn’t pick and spin discs anymore. Time for surgery then…

I was transported far and wide (including a hop across the pond) to a well-regarded hospital and spa (for Musical Fidelity brethren) for an operation by my loving owners / custodians, who assured me that it is the best one of its kind on planet earth!

Once checked-in, I met this wonderful and knowledgeable doctor who diagnosed the problem with my heart and also recommended a few upgrades (implemented at the spa wing) to ensure that when I left the hospital and spa, I would be in tip-top shape. My custodians agreed to both the operation and the upgrades and after a few weeks in this wonderful institution, I am now out, and, I am as right as rain.

My custodians (George and his family) can’t quite believe that I now sound better in every way than I did when they acquired me new about 20 years ago – the grins on their faces when I strut my stuff is all telling! I am grateful to them for taking excellent care of me during my illness – they could have taken the easy way out and checked me into any sort of promising hospital nearby, chucked me into the bin, or, even worse, sold me for parts.

I am also eternally grateful to the doctor (gentleman John) who, in addition to the superb operation (you wouldn’t be able to tell that I had had an operation if you saw me now) and the skilled upgrades, took excellent care of me as I convalesced.

To all Musical Fidelity brothers and sisters out there, ailing or not, just be aware that there is a remarkable hospital and spa with an incredible doctor for you at JS Audio, should you want / need them.

Long may it be this way!

Yours truly,
A308CR CD Player

P.S. While at the hospital / spa I did meet other stablemates (other than just those from Musical Fidelity) that were in for an operation and/or upgrades. There was this four (!) box pre-amplifier that I still can’t quite get out of my head, even though I know our paths may never cross again!

Having heard of Johns reputation over the years and with an amp and CD player in need of help I gave him a call and got booked in for repair and upgrade.
Absolutely fantastic outcome in all respects.
System sounds like never before, way better in every respect.
John is a master of his craft who cannot be thanked enough.
Cheers and more cheers

I recently bought a musical fidelity a1001 amp and after picking it up from swindon down south, and bringing it all the way back up to newcastle, plugged it in and set it all up with my system i noticed the input select lights were flickering on and off ,i decided to open it up to have a look not touching anything as its not my scene but i noticed some corrosion on the internal front panel which had rotted the whole circuit board,i had a quick look on internet to see if ther were any front circuit boards for sale but to no avail,i was just going to throw it away when i noticed on ebay that most musical fidelity stuff had been upgraded by js audio so i got in touch and wow,this guy knows his stuff”thank god”he told me to send it down and that he could fix it and also upgrade it which has all been completed,all i can say is that this guys a genius at fixing audio equipment my amp sounds amazing and all works as it should ,if you have a problem with your gear give js a call i would highly recommend him excellent job i’m over the moon thanks again john sampson🫠

MF A308 CD, Integrated amp and power amp bought ex-demo back in 2008 bi amping a pair of Jamo concert 11’s. In 2019 all 3 boxes were stage 2 upgraded. Now in 2024 the system just sings effortless grunt. Plays any type of music very well never recordings especially well. Time to audition bigger speakers.

I’d had my A370.2 since new and for various reasons after our last house move my hifi didn’t come out of the boxes. The A370 sat unused since early 2005 until Covid happened and like many others at that time when stuck at home I started to pick up old hobbies. However when the A370 was connected up and turned on it didn’t work. I gave up on it and it almost got binned at that point. Until early 2023 when I started to look for anyone local in central Scotland who could repair it. People promised a lot but couldn’t deliver. After it spending months with someone who did nothing to it other than to tell me he thought one channel was blown, and another high end dealer who thought they could fix it, but after several botched attempts and more blown MOSFETs they gave up and suggested JS Audio and John.
I called and spoke to John, explained the situation and shipped the wrecked A370 to him. He’s very busy, but he had a quick look, called me to assure me that he could fix it and gave me an estimate. He warned it would be in the queue behind a number of other repairs and would be a few months before he could look at it. True to his word after a few months I had a call from him that the amplifier was repaired and given a makeover. It’s running cooler than it used to and sounds just wonderful. Connected to my Michell Gyrodec, MF 3b preamp and driving my vintage KEF 105/3s the open, spacious, almost 3D nature of the sound and smooth yet tight control has to be heard to be believed. Thank you John, you’ve breathed new life into what I thought was going to be a write off.

I have had my amplifier from new, so over 20 years. The input selector had been playing up for some time, but not only that, it had begun to sound lacklustre. Only one thing for it. I spoke to John, who explained my problems were common for the age of the amplifier.
He explained about the Stage 1 or Stage 2 upgrade he could do, and fix any other problems, such as the input selector issue.
I went for the Stage 2 upgrade option, and I have to say it is the best money I have ever spent in all the years of listening to music.
He arranged the transport for me, and I had it on it’s way within a couple of days of speaking to him.
I’ve had it back now for three weeks and it sounds amazing. Far better than it did from new. The clarity, bass and detail, combined with the power and control it has now is startling to say the least. I am hearing things which I hadn’t heard before.
I can advise anyone in a similar situation to myself that the Stage 2 upgrade is the way to go. I am indebted to John for transforming what was a great amplifier into a whole new level of sound reproduction, one that I imagined would only be found by spending north of £10,000 on a new one. Thank you John. My Nu-Vista 3D CD player will be next. Saving up already.

Bought used around 15 years ago, my amp of maybe 25 yrs had started to hiss and crackle. John took it in to look over, diagnosis worn out. Got it back this weekend, totally transformed!
Immediately sounded impressive, now after only 15 hours of the recommended 30-40 running in it sounds fantastic. Much greater depth, detail and definition – looking forward to next few weeks/months/years!

So, after many years of owning the Nu Vistas, the long dormant upgrade bug was kicking in and off I went to a local respected Hi-Fi shop to see and hear the latest offerings. As soon as the store knew what I had, the staff nearly screamed at me to keep the Nu Vistas and send them to John for a service/ upgrade. So, for far less than the cost of the amps when originally purchased, John worked his magic. After first plug in, the immediate response was “Wow, that’s an improvement”. After the three weeks “burn in”, the system just came to life both in scale, depth and insight that gave me that upgrade well beyond that, that I thought that I could afford. My biggest critic….. the other half who “can’t hear the difference” suddenly could and was, herself now sitting down listening to her collection of CD’s! I dragged her along to a high-end Hi-Fi show and the first demo room we sat in and she turned to me and said… I much prefer the sound of our system. When I discovered that the hi fi we were listening to was £100,000+, will I be upgrading anything anytime soon? Well, I could buy the new Nu Vista pre and power combo at £45,000 or I can continue to sit her with a smug face knowing that I paid not even 10% of that price to have a pair of old nu vistas that blows the new ones away. So is it worth it the cost of John’s magic? Well, you work out the maths!

The latest upgrade from JS Audio is to my KW750 power amp and was a Stage 1 plus WBT terminals plus 1kW Audio Grade transformers. Now that the amp has had some time to “run-in” the difference is substantial with improved dynamics, transparency and clarity. Sound stage is bigger and better defined and music just flows (even more) effortlessly. Many years ago I had a KW500 upgraded which also made a big difference and last year my KW Phono pre-amp was upgraded which was again substantially better for the work that John carried out and encouraged me back to vinyl again. One more bit of kit is waiting in the wings for the upgrade magic, hopefully I’ll be able to call John and book that later this year.

I have owned my amps for 20 years and love the MF sound. I was considering purchasing the new M6 pre/power but after several exchanges with John, elected to get mine rebuilt and upgraded. They have been running a couple of months now, together with a new Rega P10 and all I can say is wow. I simply love them, so much so I want more. The sound is crisp, clear, detailed and so very tight. The separation is solid and allows us to pick out all the musical detail behind the vocals. Although they are not packing huge power they move my B&W 804s with ease and I never feel like they lack in punch or volume. I now listen to vinyl for 3 to 4 hours a day and it’s totally enjoyable. Great service, amazing rebuild, so very glad I took this route.

JS Audio previously upgraded my MF A300 amp that still sounds fantastic so had John do a Stage 2 upgrade on my CD Player including new valves. Initially It sounded better and had greater detail but 4 months on and time to run in the improvement is another level. The separation of instruments, soundstage, detail is just superb, it constantly brings a big smile. Both of the items JS Audio have upgraded are now 20+ years old and would highly recommend them.

Knowing the other repairer like the Getitfixed which they destroyed this power amp when they returned it to me.
Thankfully AudioJSRepairs which is Mr John to the rescue! Mr John completely remodified and improved this power amp significantly.
I am listening now and to my surprised, the details, botom end to mid and highs expanded the sound further than the original state of this amp. I am listening to live sound the closest possible! It’s Wow!!!
This company deserve the highest score, 10 out of 10.
I will be sending more stuff in the near future to this company for either repair, upgrades or tuning my equipment.
Very highly recommended..
Thank you Mr John

Great job. My vinyl has taken a farther step on the way to perfection. Highly recommended service, glad I decided to send my amplifier (musical fidelity A3.2cr dual mono) for repair and stage one upgrade.

John has just completed a startlingly successful repair and upgrade on my classic and much sought-after Goldmund Mimesis 9. It is now able once more to run rings around current power amp references. I have nothing but praise for his work and technical insight; you can safely leave your beloved high-end gear in his hands, confident that it will come out sound better than ever. – Jon Bower, January 2023

It’s been a year now since getting my NV 08 repaired and upgraded to stage two. I’ve deliberately given the amp plenty of time to settle in as I did now want to give a “false” report.
My initial impressions were not that great to be honest . Yes , the amp certainly was better but not as much as I thought it would be .
But after giving it more time to allow the replaced components to settle in it now is certainly much much better than an original NV 08. A change of cabling (speakers & interconnects) has also contributed to the new quality.
The amp really does sing now . Still smooth but with an openess that did not exist before . Bass is deep/ strong and effortless. The slightly recessed mid band is gone and is replaced with a vivid fleshy version.
Of course it would be very interesting to compare an upgraded and standard version as relying on our memories alone may not be as accurate as we would like. Even so , I’m confident the upgraded version punches above its weight . How much above it’s weight I don’t know as I have no idea what the other integrated amps sound like in the above £10k category

Just want to share my opinion with the upgrade of my amp – Musical Fidelity M6Si.
First of all – John Sampson is a brilliant tech-guy, he knows the MF products in details and knows their weakness.
After contacting John we clarified the upgrade – 10-15 emails and I decide to make upgrade Stage 3.
It took a little bit more time but it was worth the wait.
Now my amp sounds brilliant – more natural, more powerful, the sound is amazing!
It’s a keeper for a long time!

I got in touch with John for repair of my CD player which had stopped providing an audio output and decided to go for the Stage 1 upgrade at the same time. I’m very pleased with the improvement in sound quality. Although I’ve long appreciated the Musical Fidelity sound, the combination with my PMC speakers and M6i amplifier, (which had a Stage 1 upgrade before I acquired it) sometimes lacked emotion. Following the CD player upgrade the whole system now sounds a lot more musical and involving, it’s really unleashed the potential of my amplifier and speakers.

John is an ex MF service engineer, I worked for the company during the latter years and I’ve always been a fan of MF kit. With the sale of the company I was unsure how legacy products could be serviced and repaired.
I knew of John’s work and how highly regarded his work is seen.
I picked up an A1 from ebay, I always wanted one and found one in great condition. The volume control became noisy and the input switch became very intermittent. I contacted John and his his advise was to upgrade and service.
I said to John I wanted to retain the amplifiers warmth and musicality, the upgrade is absolutely worth the investment, I feel I now have a brand new amplifier with the Tim de P designed circuit, what a transformation. Music has come to life, organic, musically and transparent.
I can’t recommend John highly enough, he has done a fantastic job from drop off to being sent to me.
He is a genuinely nice guy who absolutely knows his stuff.

Thanks John.

Upgrade done in an extremely professional manner. All Capacitors replaced op-amps internal cabling and speaker binding posts replaced.

The first thing I noticed was that the sound is so much smoother; sounding much more like a single ended amplifier.
The smoother sound is not at the expense of information; far from it.

I can now hear when woodblock percussion is being used; the structure of the sound is quite clear.

When listening to solo male singers, there used to be an artificial zing associated with the male voice. Now the voice sounds natural as I would expect it to sound in a live performance without amplification.
Orff: Carmina Burana the dying swan is an example of this.
Imaging is great, and dynamics have improved. The Amp also seems to work better at a lower volume quite a surprise!
This amp now punches way above its weight a very relaxing detailed sound worth every penny.

John completed a Stage 2 upgrade on my A5 CR Pre, I was using a Croft Micro 25R pre, sounded good but presented a vague and inconsistent soundstage. John assured my that the upgraded pre would bring everything into focus.. he was SO right. Next stage was to upgrade my aging A5 CD to Stage 2, what a revelation. I also have an Akurate spec LP12 and am really not sure if I prefer listening to CD of Vinyl now. In all my years of upgrading and listening to music I have never ever said that. The A5 CD is now simply staggering. John’s advice and guidance has been invaluable through my upgrade journey (he also did a Stage 2 to my 550k power amps a couple of years ago)
Costs have gone up, but the value far out weighs the money I have spend so I am a very happy man…