Why is it that when I switch to the multichannel input on my receiver the volume of the bass/sub is considerably quieter than when using the digital input? Its very annoying because I constantly have to adjust the level when changing sources. Does anyone have any ideas on how to fix this?

player: yamaha dv-c6770
receiver: yamaha rx-v2600

Your receiver doesn't do bass management on the multichannel inputs. You need to set that up and calibrate on the DVD player.

If what you mean by 5.1 is SACD/DVD-A through what some AVRs call "ext in" then (again) some AVRs can do bass management for the sub. The Denon series from 38xx up do this on the "input menu" (for some odd reason, you'd think it would be on the speaker menu ). I note that it has no effect on 2.1 (duh) but for some reason when I use Dolby PLII-x for music it also seems to apply... can't figure that one out. So I would check your AVR and see if you can adjust the (equivalent of) "ext in" sub level. You may get lucky.

OK, I'll see what options are available for that particular input tomorrow. I notice that I can still adjust the level on all the speakers when running through the analog input. I don't think there are any choices on the dvd player that would fix this... that would be way too easy.

If it's a universal player, there should be settings for it. On my Yamaha, if you go into the setup stuff, on the audio page there is a speakers section where you adjust the levels. Of course, I have a different model than you do.

I had same trouble and what I ended up doing was getting the sub level quite low (-5 or -6dB) in the surround settings covering DTS/DPLIIx/DD and quite high (+10dB) in 7.1 channel analog input settings (both in Marantz SR7400). I played with DTS audio DVDs and those settings until the bass level does not depend on whether I listen in 7.1 analog mode or in DTS mode. Then I calibrated the bass level using the level knob on the sub (switching between "direct mode" with no sub and stereo with a sub - again trying to get the bass level more or less equal. Not sure how scientific this is but gives reasonable results and does not annoy me anymore.