new amp vs old amp

I'd like to share my expierences in changing audio pieces or cables. This may seem strange but I've run across this many times. On occasion when auditioning a different piece of gear or cable I would hear either subtle or no difference. But when I would put the original piece or cable back in my system is when I would realize the different characteristics of the piece or cable that I had taken out of the system. This may not seem to make any sense but for me it has become part of my auditioning pratice. Perhaps I don't have the golden ears others have, or I wish I had. ----->Ray

Ampzilla: your "brief A/B testing" makes it seem as though neither piece was warmed up thoroughly. By "thoroughly warming up" I mean powered on for at least 30 hours.
In solid state equipment it takes that long a time for the power supply regulators to attain thermal stabilization; any comparisons prior to that may be preliminary at best.

for the record the rest of my system,aside from the new and old amp!are amc cd8b,p.s audio 4.5 vandersteen model 1,and also some tannoy proto j's.im about to replace the p.s audio in favor of an older preamp,believe it or not.im going to buy a thalia,well see what happens,thanks for all your helpfull advice!!!amp.

All of the suggestions above are good ones. I would like to comment on the Dynaco ST-120. It was a great amp with performance way beyond its price and time. I owned one in a second system of mine in the 70's and recommended it to my cost conscious and tube averse friends throughout the 70's.
However, sound wise you should be able to hear it showing its age. If you could borrow someones tube amp and if you still don't hear a difference I would say that you have some rather serious limitation in the rest of your system. On the otherhand, while I don't know the Acurus, maybe its not that great an amp.

Ampzilla747, Isn't the thalia preamp you are looking to get made by GAS?

I have a little experience with the brands you are comparing. I own a Dynaco 400 and have had a Aragon 8008BB in my system for a short while. The 400's front end has been modifyed by me but even with that taken into account I believe that the 8008BB was more refined. I believe the differences should be clearly audable in your system. (I use the 400 as a sub amp most of the time)

On the other hand there are several factors that could make your observations different than mine. 1) The most likely reason is that I have not heard the exact amps you have. 2) In agreement with the others, the Dynaco was a very good amp in its day, and if the capacitors were replaced (they really do age and dry out) has the potential to be very close to the Aragon. To my knowledge, transistors do not deteriorate with age and the Borbely designed Dynaco 400 is not really much different than the topology used in the Aragon 8008BB. The biggest difference is in the power supplies where a toroid is used in the 8008BB. This difference should be most audable in the bass. 3) I will chime in with everyone else and agree that there could be a bottleneck else where in the system. I have a non working PS Audio 5.0 that I could repair and give you some feedback on it in the future. I have heard PS Audio equipment at trade shows and I feel that it is reasonable stuff and well suited for the rest of your gear.

I share your desire to use older equipment. I upgrade the parts as required and I get a kick out of someone saying "That old stuff sounds that good?". I woulg really like to get an Ampzilla (and many others) after I get rich.
Feel free to email for help on repair if you want. Chris