Scratching my head...Bluesound Node 2i direct to amp

Hello friends, long time lurker, first time poster. Earlier today, I hooked up my Bluesound Node 2i directly to my PS Audio Stellar S300 amp, just as an experiment and used it as preamp. Everything that I read would say that this would be an inferior way to listen to music to usual setup. 
My usual setup is a 2.1 system that goes like this Bluesound Node 2i<Bifrost 2<McIntosh MAC-3 (I use this as a preamp I know that it wasn't its original intention when made)<PS Audio Stellar S300 amp<Elac Carina, sub is an SVS 2000. With the Bluesound direct to the amp, the sound was cleaner, more alive, and had significantly more bottom end from the Carina's (note-when I ran the Bluesound direct, it was just as 2 channel the sub wasn't running), so much so that I was shocked when I looked over at the sub and remembered that it was off. 
So my question is this, how could this be? Is my "preamp" the weak link? I really felt like the Carina's came into their own running direct to the amp. I know that the Bifrost 2 is a better DAC than the internal DAC of the Bluesound. Only thing that I can think is that it maybe time to upgrade my pre :). Any thought's friends?

Thanks!

*Source material was a variety of MQA and CD quality tracks from Roon