Hello Erik. The bass amp needs to be higher gain than the Red Dragon S-500 I'm using to drive the satellite section of my large Legacy Focus clone/diy speakers. These use Eton drivers, 2 midbass, midrange, tweeter per side, and these drivers are significantly more efficient than the woofers. When I first acquired these speakers, I bi-wired but did not bi-amp them and I was shocked out just how little bass I was getting despite 4 12" woofers. Eventually, I did bi-amp, using a pro amp with the volume control pots to gain-match to a large SET in the colder months and a gainclone in the warmer ones, via the RCA outputs. My source was a Raysonic 228 cdp which I ran directly into both amps simultaneously. The player was tubed and the RCA outputs were connected to the valves while the XLR outputs were solid state, exactly what you'd want connected to the bass amp.
I'm now using either a Bel Canto DAC 2.8 or Audio Alchemy DDP-1 and the balanced outputs are the ones I use to drive the Red Dragon powering the satellite section of the speakers. I have to run the bass amp from the RCA outputs which are half the gain of the XLR outputs, so it becomes necessary to have a higher gain amp on the woofers. I use an NHT X-2 active crossover only on the bass drivers and it allows for +10dB of gain, which full up with the D-sonic amp (rated gain of 26dB), is just adequate on most material/recordings, but can be insufficient on other material where extra bass would be desirable. I did insert an active preamp, a Kingrex PREference, between the crossover and the bass amp briefly. It gave me plenty of additional gain but lost a bit of detail and could easily get boomy.
With the Jaton amp as the bass amp, with a gain of 32dB, I seldom turn the NHT X-2 up all the way so, it's obvious to me, going with a higher gain amp is the way to go. I'm just looking for a decent but affordable class d amp with sufficient power and that higher gain to take over the bass duty. I know the mentioned Channel Islands D-500 monoblocks fit the bill but really don't want to spend quite that much and then I'll need to get another matching power cord for the other bass amp.
So, I think you'll be able to see the importance of a higher gain amp in my application and yes, there are low-gain class d amps. I've seen a few listed at or below 20 dB, which would be useless as the bass amp in my system.
