Here it is verbatim except for his name.
My purpose in publishing the review below was to offset some of the negative reviews of the STA-9 that I felt were unfair...it's a very nice amplifier. My wife likes it too and she has a good ear. -XXXXXX
Opinions Vary: My STA-9 sounds very much like a Nelson Pass class A 50/50 watt amplifier which I owned and sold due to massive heat generated. I currently own and absolutely love 2 restored Pilot 232 EL84 amplifiers...so I think I know what a tube rectified harmonic tube amp with NOS tubes sounds like. Does the DSTA-9 sound like my Pilot 232? No, not even close. But the STA-9 sounds very close to a Nelson Pass class A amp to my ears (grain free...smooth, clean, clear top to bottom)...and, in this regard, the sta-9 performs way above it's $$ class...but I can understand how the STA-9 could sound flat given a poor pre-amp match.
With my tube pre-amp, the STA-9 is plenty lively/ dynamic...and very very clean. If I were to be super critical, bass cold be a little tighter...but of all the less than perfect characteristics an amplifier could exhibit, this is the least objectionable...Highs might be a little recessed as well but the benefit is a complete lack of sibilance which is very much to my liking.
Here's the positive, I can listen to this amplifier all day...and it is PLENTY lively with my tube pre-amp...my only urge is to play it louder...My preamp is EE MiniMax, tube rectified with Miniwatt E80CC pinched waist 12au7 variants...like others have commented, the STA-9 must like tube pre-amps...as some of you know, not all tube pre-amps are created equal...go with tube rectified...(if it is SS rectified, yo may as well go all SS) and, tube rectification is naturally immune to RF.
All my components are plugged into a Chang light speed power line conditioner...so RF is minimized in my system as a whole....I should note that there is a very small, easy to miss red 115v - 220v switch on the bottom of the chassis...one needs to select the setting to match one's power...my amp came set at 220 and I needed to reset to 115. Right out of the box, the STA-9 sounded really bad...but after 2 hours, it sounded remarkably refined...ofcourse I use my own power cords that are already burned i...not sure how much burn in this amp requires, but I suspect it's less than most. Flat, lifeless? No!
For comparison, My pre-amp has 2 sets of RCA outs...so, I sent one to the StA-9 and one to a very nice sounding dedicated headphone amp...and switched between speakers and headphones using the same source...speakers through power amps NEVER sound as good as headphones, right? Well the STA-9 held it's own very very nicely.
Is it fast? Yes! Are transients (rimshots) handled well? Yes! Are male a female voices slightly forward from the plane of the speakers? Yes! Do I like the StA-9 as much as my Pilot 232s? Honestly, no, the Pilot 232 are my all time favorites...but the STA-9 is much more practical and much less heat generating...as someone who has owned many, many highly regarded amp and Pre-amp combinations, I can honestly say I am very satisfied with the STA-9 and it is by far the easiest and friendliest to set up and use...In my personal experience...if you don't like the sound of your STA-9 it's either a pre-amp issue or possibly speaker match or your STA-9 is just not the same as mine. Highly recommended based on my experience...and no, I am not affiliated with any manufacture...I
BTW: I own a highly regarded pair of $2500 focus Audio FS68se speakers (smallish speaker with Scanspeek 9500 tweeter and Eaton 5.5" woofer) This is an amazingly musical small speaker which pairs well with my Pilot 232 El84 tube amplifier. Well guess what? The STA-9 paired wit the new PSB Alpha p5 speakers sounds remarkably similar at less than 1/5 the cost!