I have an Aiyima A08pro class d amp. It has a 3.5mm AUX variable output I have connected to a powered sub-woofer. The amp volume controls volumes for the entire 2.1 system simultaneously. My question is what will happen if I add a tube preamp ahead of the A08; i.e. where is volume controlled? It seems to me that turning up the A08 as loud as I'd ever want it would do the trick, then using the preamp volume itself would raise volume across the 2.1 system uniformly. Is that right? Thanks!