My experience with Adcom amps is kind of dated (late 80s to early 90s) but I did have access to their line as a salesman and purchased several models on accommodation during that time. My memory of those two amps specifically are, the 555 had good power, decent sound stage but somewhat limited air around musicians on stage, upper mids into highs tended to get a bit bright when asked to open up the volume. For all that power, I always found myself turning it back down to tame the edge that would start to appear and this was on many brands of speakers. The 5400 came a few years later on, still had a few pairs of the speakers from the first go-round with 555, 565’s & 585-SE. The 5400 seemed well balanced, smoother mids and highs with less grit or sizzle, sound stage was admirable for a budget amp with better spacing around musicians. The only slight down side was the bass when volume was elevated enough to demand more control and reserves. This is where the 5400 would run out of gas compared to the older big block style amps.
I don’t listen anywhere near as loud as I used to and if given a choice between those two amps now I would lean on the 5400 for a more musical presentation.
I don’t listen anywhere near as loud as I used to and if given a choice between those two amps now I would lean on the 5400 for a more musical presentation.