how do i get more bass w/o adding a sub

Apart from the issues raised by Almarg, I would think that you might improve the bass response some by finding and taking advantage of bass frequency nodes (or avoiding nulls). This can be more easily done using a SPL meter at the listening position and playing a disc with bass tones at 1/3d octave levels, measuring (and charting) the bass response as you move speakers about. Finding a position with a bass node about 80hz (60 to 100hz) can be a blessing for small speakers if the location doesn't produce a corresponding null at a higher frequency as it often can do.

Almarg is probably right. It's your pre/amp combo mismatch causing this. If you, demo a good integrated to see how much it helps. I can tell you the NAD C390 has fantastic bass and a built in DAC.

Room treatments.... Bass traps behind the speakers, and so on.

If your amp is plugged in your power conditioner, try plugging it direct into the wall socket. The silver streak may also be adding brightness. Test that out by substituting some PBJ cables or similar all copper.

Set up your equipment properly -- buy Jim Smith's Book. Your speaker set up is critical and time consuming.