We all hear differently. Let me say it this way, DACs direct to amp have more "detail" but I find it more fatiguing in the long run. Digital attenuation reduces the volume by throwing bits of data away. That's why some don't like it. For me, the better the preamp, more gets through but still retains the musicality that I love.
A dac direct to amp seems impressive at first, but too much detail takes the enjoyment out of it.
Have you compared a preamp to no preamp in your system? If you love no preamp, great, you've saved some money. I've compared it many times with several dacs and many preamps and I always prefer the preamp.