Amp Gain/Preamp Output Impedance Matching

I wanted to give you a summary of my adventures with Amplifier Gain and MSB Output Impedance matching.I use the MSB direct to my amp.

My Benchmark AHB2 amp has three gain settings (9db, 17db, 22db). I began by selecting the 9db setting and the 300 ohm output on the MSB Discrete. I found the treble a little hollow sounding so I changed the MSB to the low output setting and it sounded much better. I then tried the amp at the 17db setting with the MSB still at the low impedance setting. This resulted in a move forward sound with more bass impact but the overall soundstage was less transparent. So I returned to the lower amp 9db gain setting. It was then I discovered that the Word Clock sync had not been activated on the Aurenser N20. After activating it the sound had a dramatic improvement. As a final test I realized I had never tried the MSB high output with the Clock synced and the 9db gain on the amp. That setting was the secret sauce.  A perfect match of clarity, bass impact and soundstage transparency. I run the MSB volume between 85 and 92. So quite a journey of exploring these settings.

Now I will have to do it again as I just ordered a new Accuphase P-4600 A/B amplifier which also has selectable gain (28db,25db,22db and 16db). When it arrives sometime in April I will be going through the permutations of gain and output impedance again.

As a side note I was at Overture on Tuesday auditioning the Bryston 4b3 Amp with the MSB Discrete. The amp has two gain settings (23db and 29db). They had it set at 29db and I noticed that the MSB volume was running between 67-72. I don't know what output impedance was selected for the MSB. It sounded fine so I guess the results of these parameter permutations are not absolute but also amplifier dependent. I think Accupahse recommends the highest gain setting. but I will certainly be exploring all of them.