I really don t believe what is written above. I am using this amplifier for 2 years now and it performs breathtaking and melliflous sound. This amplifier is very fast, reproduces high dynamic and, what is the most important for me, makes details significantly convex. If someone has to leave the room when s9 is playing it means he has ears problems or drastically unmatched system!
However I agree that the best cables are copper cables( in my case Audio Note Isis, both interconnect and speakers) for this equipment, and I would also suggest really detailed transport or dac. Good solution for this purpose is Unison Research Cd Due player with dac (sabre in this case 32-384 khz ) It really works pleasantly.
Another important part of story are speakers, in my system Focal Electra 1027 Beryllium. Beryllium tweeters are genius due to the fact that they reproduces every single sound hat has been recorded on the Cd or hi-res file. At the end I will tell that I took part in many AudioShow exhibitions in Poland and one thing I am certain- It would be. Ery difficult for me to find another configuration of equipment. Maybe few 845 tubes amplifier I could accept but the price is at least tripple (For example absolute - Unison Research )
And........ I really love the glittering and shining of the sv-572 valves!
So to my predecesor in rewiev above - please try this configuration and you will be sonically rewarded :)

Stunning sounding single ended class A amp that entertains like few others and delivers the sonic goods with aplomb. An addictive blend of musicality and muscle with a solid, rounded tuneful bass, an expansive and expressive midband coupled with the sweetest highs, makes for an utterly engaging experience and long listening pleasure. The music ebbs and flows in an organic way only the very best components can conjure with unfettered dynamics, explosive transients, and highlighted tonal contrasts and shading that simply stagger...
System matching may be an issue (like all components) if your ancillary equipment is not up to the job but let me tell you fellow sonic heaven seekers that when coupled with Magnepan 3.7i speakers and connected with Transparent Ultra cable a certain magic occurs that even Dynamo would find hard to believe!
System conprised of :
Turntable - Roksan TMS/Funk F.XR/Koetsu Jade Platinum
CD Player - Lector CDP 707/7TPS
Amplifier - Unison Research S9
Speakers - Magnepan Magneplanar 3.7i
Cable - Transparent Ultra
(All equipment 2014 Spec)

This amp is horrible. The shrill of the SV572 sounds thin ,sterile, annoying and makes you want to leave the room and make coffee. Sounds loud and powerful but you just keep turning it down. Change i/p tubes to amperex then mullard and still not enough warmth .Change interconnects from chord sig to cardas all copper extra warm and change speaker cables to pure copper. Get rid of any silver . Yter makes ears bleed. Now I can stay in same room to llisten but no detail or inner resolution. May only work with UR cd player as smooth and warm as source. Cannot drive sonus faber speakers. Bass maybe ok with dynamic i/p tubes but thats it. Cannot buy o/p tubes anywhere only UR and they charge double. Disaster amp. You need to home demo or run away as fast as you can. Build quality and looks mean jack when it sounds this bad. I may have just saved you from Hi Fi Hell !