You are either a glutton for punishment or just got a new can opener, and wanted to see what kind of worms were in this can!
In spite of the fact that basic amplifier design has not really changed that much in the last fifty or sixty years, the differences are potentially extreme. Many of the changes have been designers adding their own tweeks to a fairly basic design.
At the risk of being overly simplistic, every connection is a loss of signal, and in my experience even things that are not in the signal path affect the signal path.
Lots of people were impressed when Nelson Pass went with a single gainstage with the newer X series amps. The sound benefitted from the shorter signal path.
I currently own my second Krell amp, but both of mine were from the FPB series. I can tell you without hesitation or qualification that there is no treble roll off with either of these amps.
As far as your question about spending money and getting a return for your investment, I will relate another experience. I had an Aragon 8008st amp. It was 200 wpc doubling down as the impedance was halving, down to 1 ohm. For no good reason I decided to sell the Aragon and replace it with a Krell FPB 200. On paper the two amps were virtually identical. There should have been no real difference. In my listening room the difference was night and day. Rather than going into all the details, you can see my review, if you'ew interested. http://forum.audiogon.com/cgi-bin/fr.pl?ramps&1043208372&openusid&zzNrchy&4&5#Nrchy
You stand to gain a lot, or you may gain nothing, but don't be fooled by specs and people who want to talk about the science of audio...
What was the question again???
In spite of the fact that basic amplifier design has not really changed that much in the last fifty or sixty years, the differences are potentially extreme. Many of the changes have been designers adding their own tweeks to a fairly basic design.
At the risk of being overly simplistic, every connection is a loss of signal, and in my experience even things that are not in the signal path affect the signal path.
Lots of people were impressed when Nelson Pass went with a single gainstage with the newer X series amps. The sound benefitted from the shorter signal path.
I currently own my second Krell amp, but both of mine were from the FPB series. I can tell you without hesitation or qualification that there is no treble roll off with either of these amps.
As far as your question about spending money and getting a return for your investment, I will relate another experience. I had an Aragon 8008st amp. It was 200 wpc doubling down as the impedance was halving, down to 1 ohm. For no good reason I decided to sell the Aragon and replace it with a Krell FPB 200. On paper the two amps were virtually identical. There should have been no real difference. In my listening room the difference was night and day. Rather than going into all the details, you can see my review, if you'ew interested. http://forum.audiogon.com/cgi-bin/fr.pl?ramps&1043208372&openusid&zzNrchy&4&5#Nrchy
You stand to gain a lot, or you may gain nothing, but don't be fooled by specs and people who want to talk about the science of audio...
What was the question again???