pre-amp vs dac straight to amps

"for me, it's through the preamp that has lots of bass punch and impact!"

This is because your DAC has a high-impedance output stage. Going direct is superior only if the DAC has strong drive on the output stage. OP-amp outputs usually dont cut-it.

Steve N.
Empirical Audio

I have a PerfectWave DAC and a VAC Renaissance 30/30 amp and much prefer it with my VAC Standard preamp in the middle. That being said, there is additional detail without the preamp that works for some music and recordings, but there is also added stridency and edginess that makes it much more unpleasant for others. All in all, I find it more musical with the preamp; also a little bit of forgiveness in a system makes for pleasant listening across a much wider variety of source material.

I have been going back and forth using a Jeff Rowland Capri PM in line with a Berkeley alpha 2 DAC feeding a Modwright KWA 150 SE and the Berkeley direct has greater transparency, detail, air and lower distortion BUT the center fill is oddly thin and the sound is slightly less meaty. To my ears the preamp contributes a subtle layer of fine grain and less clearly defined instrument outlines. It is odd but the straight up alpha 2 is objectively superior at revealing music information yet I still miss aspects of the added noise the Rowland contributes a warm, human character that is compelling. I am truly conflicted.

Cm - Based on your observations, it is likely that the current drive from the Alpha is not as good as the preamp. The enabler for DAC direct to amps is the DAC output drive.

This is the reason why most passive resistor-based linestages kill dynamics. They reduce drive current.

Steve N.
Empirical Audio

IME, going direct is not a cake walk - it takes work to get right. This configuration is going to reveal flaws upstream. The simple choice of the power cable or interconnect you use on a component will become critical since any anomaly will become very evident and very annoying.

I'd try swapping out cables until I find a configuration that works. At the very least you are going to learn more about your system and the capabilities of your components.