DVD player and amp. No preamp ?

[rpb]

I bought a used Oppo DVD player for next to nothing that has 5 channel analog outputs. I have a 5 channel amp with no volume controls. The Oppo has a volume control for the pre-outs that are controlled by the remote.. Should they work well together? I hooked them up, and it does work, but I'm having issues getting the bass right. The sub out seems to have a steep low-pass filter, but maybe at 100hz, or a little higher. I can't find any specs on the low-pass filter. I hear absolutely no vocals with my ear to the sub, but the bass sounds murky so far, like it's going too high in frequency. The player even has delay settings for the sub, so I can delay it to help get the blend right. Is there any issue electrically connecting this way? I have a 6 channel pre-amp I can try to see if things improve, but I was hoping this simple setup might work without it.

[wogg]

The player's sub output is probably just the LFE in the 5.1 stream. Most AV receivers will use bass management and add the low frequencies from the other channels in there too, and add proper HP / LP filtering. That's probably what you're missing.