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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
klipschking
tabl10s's avatar
tabl10s
1,067 posts
 
Sell and get a pair of 565's.
bbro
191 posts
 
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.
johnss
564 posts
 
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.
keyd1
7 posts
 
Hi, just bought a used Adcom GFA 555. I believe it's the original model. Mark 1 is it?  Does this amp have an impedance switch on it, or does it just adjust impedance according to the speaker load? My first time going with 4 ohm speakers. Thanks.
213runnin
914 posts
 
No sir, there is no impedance switch.  That's for weaker amps or girlie receivers that have no jam.  It'll be fine with your 4 ohm speakers.


On the other hand, you might want to consider the age of the 555.  Shine a light inside the amp to see if there are any bulging or leaking caps, as a 30+ year old amp can develop issues.
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