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Dec 20, 2017 by James Ross
Item Repaired/upgraded: AMS35i/ AQ Forest speaker cable 

I decided to upgrade my AMS35i at the same time as fixing the volume control issue.
I wasn't particularly expecting much as i was already pleased with its sound but John was confident enough he could improve it that i decided to put my trust in him. 3 weeks later I am still just blown away with the outcome. The results are improved in all areas without losing that beguiling musicality that made me buy the amp in the first place. Most noticeable is a cohesiveness that i didn't know was missing, increased insight and improved sound-staging. A separate repair to some pre-owned speaker cable also repaired by John (terminations and jumpers) has further improved the set-up. Just mind blowing.

But the main reason for this testimonial is John himself. His honesty in an industry I perceive as filled with a lot of smoke and mirrors has taken away a huge amount of frustration that had built up through attempted improvements to my system guided by hi-fi shops. i can whole-heartedly recommend John and his service.



Nov 30, 2017 by David B
Item Repaired/upgraded: A370, P270, MVT 

It’s a tall order properly driving stonking great come-and-have-a-go if you think your hard-enough type speakers (B&W 801D). However, the supreme A370 on bass duties (John even biasing sonic delivery to favour lower registers) now weighs a gazillion tonnes and gives truly heroic performance (and I’d imagine is edging into crazy SA470 territory). I dread to think how much current it now chucks out. And the (wholly underrated) P270 (on mid/tweeter) has become barely lift-able, is as smooth as hell, and matches, or betters, the A370 pre-upgrade. The downside is that there’s now a black hole in my listening room with its own gravitational field.

A difficult, complex job, completed with passion and skill - bigger transformers, internals rewired, high-end Mundorf caps throughout, WBT connectors ... and I’d imagine a whole heap more too. John also added two sub-woofer outs as part of a heavy MVT pre-amp modification (where I can now take the bass into the stratosphere). Its sounds beautiful and lovely, I grin from ear to ear listening to this rig. I’m getting on a bit but it’s never too late to be astonished and amazed.
And one of the nicest things about JS Audio is the banter you can have with John himself. He knows his onions all right but, more than that, he is a true quintessential gentleman, with your best interests always at heart.

Heartily recommended. Superb and a profound transformation. Thank you, thank you.

Better than new

Oct 23, 2017 by James P
Item Repaired/upgraded: MF CDTube / Cyrus2 / PSX 

After 15 years in storage and not working JS repaired and renewed my lovely MF tube CD player, complete with super Russian valves. After such a transformation I had to get the equally old Cyrus 2 and PSX upgraded. The combined effect is astonishing. Great advice, follow up calls, very efficient. Highly recommend!

Awesome transformation KW-550

Aug 21, 2017 by D.L.Whitton
Item Repaired/upgraded: KW-550 

After years of not being content with my system I let John do the full upgrade of my KW550. Being curious after John I picked it up when it was ready, which was quite a trip living near Amsterdam. But meeting John made it all worth wile. What a nice and knowledgeable guy he is! But after installing the amp back in the system there was a definitive improvement, but still something annoying me. To the point that I sent the amp back to John for a checkup.... Shame on me!! The amp appeared to perform flawlessly in John's system. John politely suggested my beloved, and I thought perfect, pair Dynaudio Confidence C4 might be the cause of the annoying highs and lack of imaging. I must admit it took some time to accept this as a possibility. I then had Ben van Leliveld, owner of Acoustic Matters, take an acoustical blueprint of my system and listening area. Ben does this for high end systems but also for (famous) recording studios and for demonstrating rooms for high end dealers. Apart from very accurately determining the acoustical problems of the room, Ben immediately found the Dynaudios to measure anything but flat. These were newly bought speakers! John was right all the time: the Danes were to blame. The acoustical problems were solved relatively affordably, and anyone should treat oneself to do this because it is by far the most effective way of finally hearing what a system is really capable of! Then after selling my Dynaudios I went on a search guided by Ben van Leliveld. I visited some dealers to listen to speaker systems and almost broke my back on the process because Ben strongly advised I do all the listening with my own KW550. Now comes the fun part: although the speaker dealers knew (or knew of) the KW550 they looked a bit as if they considered it oay but nothing special and certainly not good enough for them. But all and I repeat all of them became very silent after the KW550 started playing and warmed up a bit. They listened without comment and afterwards said thing like: 'you should never sell that amp' , this doesn't sound like a KW550 at all' or 'you have to pay at least 20.000 euros to get something as clean and powerful as this' So I am now listening to a pair of Harbeth 40.2 in an acoustically treated room and the difference is unreal. Finally I understand what a profound and unexpected change John did to the KW-550. There is a wide deep stable stereo image. No harshnes. Everything is tonaly correct. Instruments and voices sound so natural. Finally there is MUSIC and I am enjoying it. The job John did to the KW550 is amazing! Thank you, John!

My X-A100R

Aug 19, 2017 by Laki Sandhu
Item Repaired/upgraded: Upgraded 

What a contrast... I had John upgrade X-A100R amp which has been part of life since 1999... I decided that vintage is the way forward and luckily enough Ebay seller Clifton from Eastcote had a set of near perfect MC-5 speakers up for sale... The upgraded X-A100R and these MC-5 speakers are unreal... Task... How do I connect the 2 pairs of MC-4 speakers to this setup without having an ASBO???? .... I am stunned and enjoying the sound and depth from the amp coupled with some sublime speakers..... Thank you John... Great Stuff!

JS Audio Repairs , USA 5.0 5.0 108 108 What do you do if you own a fantastic 1998 Stereophile Class A CD Player that won't play discs anymore? You take it to John Sampson. Straight away, John knew the entire laser mecha