Amplifier Modification

Can solid state amplifiers be modded to obtain higher input impedence, so that they can have a better chance at matching with a wider variety of preamps, specifically tube preamps?
Nelson Pass put an auto-former on the front end of one of his First-Watt amps. I suppose something like that might work?
Thanks for the response. I think I will run this by a someone once I see how my preamp turns out.
By adding deeper negative feedback and adjusting bias(offset) current accordingly.
You will then jeopardise stability of the amplifier for good and will need lots of trial-errors to get it stable.
Highly UNrecommended procedure.
Thanks for the response, Marakanetz. I found the info I was looking for, and there is no need for me to worry about impedence level. The ratios will be fine. Now I can pursue my tube preamp. Thanks again.