What is the input impedance of the Sugden A21aP power amp?
I have a wonderfully sounding class A power amp, essentially the power section from the revered Sugden A21a (the 90's version).
But I have been searching wide and far for specs on the input impedance as well as the power output rating on a 4 ohm load (it's 25 wpc into 8 ohm).
Can anyone help? I don't have access to measuring tools.
The reason I want to know is that I would like to match it with my Audio Note M1 tube preamp, which has a high output impedance of between 2,5 and 5 kiloOhms. This translates to a weak bass performance/bass rolloff when playing into the Sugden. With my cheaper transistor preamp, I don't have this issue.
If I know the specs of the Sugden, I can have my Audio Note dealer modify the M1 with a feedback loop to lower its output impedance to match.