the A5 is a wonderful amp, very lively and detailed, 250W and
has plenty of power for both my Spires and Montanas. It's solid
state and at times is a little too hi-fi for the Spires, hence my
flirtation with the Sim I7 and the MF KW550. You're probably
right, the 550 will most likely have a similar sound to the A5
which is fine with me, but i thought the tube presence might
be a little smoother for the Spires. I might still prefer the A5
for the Montanas . I read one customer's comments that said
he had a hard time hearing a difference between the two MF
amps which makes me pause, but it could be the minor
difference from the tubes that makes it all worthwhile with
the Logans. Or i could buy the Sim. That looks more likely
now that the 550 appears to be sold. Just wish the Sim had
at least 200W. I love using only one remote though with the
MF equipment.