Adcom GFA 555 amp upgrades

Hi. I own an Adcom GFA 555 amp, and I'm wondering if its practical to upgrade the amp to the standards of the Adcom GFA 555 series II (or better). Love the power and flexibility of this amp, as it powers my 4 ohm Kef Reference 103/4 towers with ease, but you know how it is, we audio junkies are always trying to squeeze a bit more fidelity out of our gear. Many thanks! -David
You might want to call Musical Concepts. They specialize in Adcom Mods plus more. Been around for many years and have gotten some very good reviews.
Joe Nies
My dad got a gfa 555 years ago and it was the one that originally gave me my Audiophile epiphany. He still uses it and it's going strong. I don't know if you'd really gain anything by going to the series 2 though. What about that one designed by Nelson Pass (I can't remember the model)
The old 555 is a decent amp but I wouldn't do a factory upgrade, as you'd be better off selling what you have & buying the different version.

If you really, really want to hang on to this amp & price isn't your main concern, you can get someone like Musical Concepts to mod it.
Musical Concepts modified my GFA555 many years ago with great results. I eventually gave it to my nephew who loves it. John at Musical Concepts told me that the Mark 2 version was warmer and more laid back but had less resolution and weaker bass, so he thought it was not an improvement over the mark 1, although some people might like that sound. The question is whether it is cost effective to do a complete mod/upgrade on such an old design, when you can buy a better amp for the price of a complete mod/upgrade. That is unless there is something about the GFA555 you really like and would like to keep but just improve upon.
See also this recent thread:
"Adcom GFA-545 - Modify or Move On?"

Sell and get a pair of 565's.
I had a Mark I and Mark II. I had the Mark II modded by Musical Concepts since it was a later model. Much improvement. However after much comparision I found the original unmodded Mark I to my preference.
you'd probably be better selling the mark 1 and buying the 555 mk2s on the used market if you want an Adcom with a larger supply. But even then the 555 mk2 is not optimal.