Some time ago I bought Italian Stage both (I alternate as monitoring) X215AUB and this model of the IS series at the output plays quieter at the beginning, but it is the design of the amplifier. In fact, it is sometimes even better against (overexcitation). They play the treble (softer) than the X series, the bass of both models is kicking, hard and fast with the 15" and better, apparently (higher filtration of the capacitors :-) At home or in small spaces it is enough use through the RCA input. For larger actions, Jack 6.3 (balanced cables) because you can use a louder GAIN potentiometer to adjust the gain of the input amplifier. The best combination I have tried is with any BEHRINGER console .) It plays softer on the bass, so it balances it out (hard.) A small ailment can be heard all the time when you turn it on (transformer hum from the bass player), but it disappears at higher volumes :-)