I own the X-150 which is the same amp less power. This is the best amp I have owned. I have had a Odyessey amp, a McCormack, a Belles, a hybrid 2 stage Llano 300 watt side beast and a CJ amp (which I liked better than all the other amps). I have read that the newer .5 Pass amps have a warmer more natural mids like the Aleph amps. I don't care. The original series sound just as warm and natural as my CJ amp in the mids(which did the midrage best out of all amps I have compared it to until the Pass) and it sounds right everywhere else. I have very good ears. I am a professional jazz pianist and I know what live sounds like. This amp is the closest I have been to the real thing. Haven't heard the newer amps, but I bet they are slightly better and not worth the big $$$ to upgrade. - Jeff