I have loved my NV-600 from the off for its combination of unfatiguing smoothness, detail and power, but was curious to take it as far as I could, seeing as it will be a destination amp for me. Interestingly I actually preferred the sound overall to the NV 800, which to me, sounds a little more forward and bright, albeit still stunning.

John is a remarkably interesting chap to discuss hifi with and his knowledge inspires great confidence. He knows what to leave alone, what goes wrong with each item and what to replace. He could even explain the difference in sound I perceived between the 600 and 800.

I had the stage 2 upgrade on my amp, so went the whole way. John explained it would seem drier and a bit inconsistent for a short while, before settling and could take a year to stop improving!

After popping it back into the system, it did seem a little inconsistent for a while; maybe 2 weeks. By that I mean it would sound slightly different on different listening sessions. More full, more lean, more impressive, less impressive day to day. I left it on for some extended periods while it was burning-in to speed things up. I could sense changes in performance straight away, but it probably took about a month of on and off-listening for it to fully settle and stabilise. Now I feel I can give a valid review.

The standout improvements are:

The amp now seems to have limitless power and drives my PMC speakers with effortless authority. Bass sometimes seems drier and firmer, as it is more accurately reproducing the recording (much as a better turntable will show a tightening of control)….but, when a monster transient or genuine, full bass hits, the shock is thrilling and hard to believe. The latest Dire Straits MoFi pressings are a thrill ride.

However loud I play it, it just does not seem to get fatiguing….again this is probably the unrestricted power now taking control rather than being stifled and losing grip slightly due to the original weaker components. I find I have to be careful not to push volume too high in the interests of my hearing, as my brain doesn’t register that it is loud!

At lower playback volumes the amp sounds much more balanced than before, with a firmer, richer bass.

I think there has been an improvement in spaciousness and air around components of the music, but this is less clear than the other changes.

I have had the amp back for about 4 months now and can highly recommend the upgrade. Not only does it sound better, but hopefully the high spec components John uses will mean it is under less stress and is potentially more reliable long-term. I love it even more than before, as it has just the same character as always, but has extended its capabilities in all directions.