Yeah, Spook, I have the same DAPs as before with the old 846 (namely, the Galaxy S1, S2, and Note 3). I still have the Clip+, iAudio 9, and my old Touch 3G. Now, I have the Touch 5G and FiiO X3. I may break down eventually and try one of the "uber-DAPs" (HM901, AK120, or the upcoming ones like the X5 or something). The UI of the X3 has me thinking more about a DAC/amp thingy that connects to an existing familiar device.
I'm not disappointed with the bass of my new 846. It is still good. Plus, nowadays, I don't need louder punchy bass like before because I drive a quieter 2014 model truck.
What I remember most about "burn in" (of the old 846) was improved mids and highs just a few days prior to earpiece failure.