The volume control on the trinnov is digital. The volume level information is contained in the digital signal the Trinnov sends to the downstream DAC, so the downstream DAC and the subs using the DAC in the trinnov will keep their volume levels in synch. The only thing I cannot do is use an analog 2 channel tube preamp downstream in this setup. The only way to keep the tubes in the chain is to get a 2nd 2 channel analog preamp for the subs, play the Trinnov at unity gain and control the two preamps with a macro on programmable remote control that keeps things in synch. At some point I thought about doing this, but I now think it is too much of a hassle, so I will first evaluate the Trinnov using the digital volume control, and second with my MCH analog preamp (six shooter) downstream, and see what works best. By the way if you want an analog volume control, you can get two passive placette preamps - they can be chained together and do 4 channel volume control for your mains and subs. Apparently this is a very transparent solution, but not cheap, especially if you need balanced.