I was using the Musical Fidelity Tri-Vista 300 amps on my Altos, which I still have and need to moderately repair. I switched recently to the ASR Emitter II Exclusive, which drives the Altos much better overall, but they initially sounded too bright, so I flipped a couple of dip switches inside the main unit to calm down the tweeter a bit. Now they sound fantastic. The ASR amp has better bass control than the Tri-Vistas. However, the Tri-Vistas probably matched better overall. I've discussed the Focal Utopia line with dealers as well as with some folk here, and they have said that there heavy impedance curves with the Altos and so your best bet is powerful solid state amps with perhaps a tubed preamp if you prefer. At some point, i'm going to be selling my Tri-Vista amps, which are in 230 volt and can be converted. The repair work will involve resetting the RCA inputs, which are disintegrating on the inside because of the plastic piece connecting them to the circuit is falling apart. My plan was to send the amp back to MF in England and have better RCA connections made to the circuit board and then go through the entire retuning process. If you are interested in this amp and would like to do that work yourself, contact me and I can sell it to you at a good price.