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.
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.