need good minimalist preamp or headphone amp to actively drive woofers in a biamp setup


I'm biamping a pair of custom speakers, kinda like a Legacy Focus clone using mostly Eton drivers.  I'm going directly from the source, either a Consonance Droplet 5.0 or a Raysonic 228, into a four channel Jaton amplifier.  The woofers are a little less efficient that the other drivers so the bass, from a quad of Peerless 1259 woofers, is not what one would expect or desire.  In the past, I've used either big integrated amps to drive the woofers or pro amps to good effect but I really like the bass from the Jaton amps.   So, I would like to add a minimalist preamp between the cdp and the amp driving the woofers.  I tried a Parasound ZPre II and it did the job but obliterated  fine details so I need something more revealing.  I'm considering the Morrison Elad but would like to hear other options.  I'd even consider a good headphone amp though I have absolutely no experience with them and I don't want to run the bass through another DAC as I really like the sound from either of my current cd players.  I'd like to spend around $500 or so for this project, no more than $1000 please on the used market.  Many thanks for helpful recommendations!
lcherepkai
Why not use an active crossover? Behringer makes an inexpensive one.
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Thanks for the responses.  cleeds2:   why would an active crossover be the right choice in my situation?  The speakers have built in crossovers and I paid a member here, years ago, to improve them with better parts.  I couldn't comment on what was done as my DIY skills in this area are non-existent but the sound noticeably improved.  Clarity was increased as was the definition of images.  Things were more focuses---you know, a veil was removed.

Elizabeth:  I'm a transparency and resolution freak.  I'm running source directly into the cleanest/most transparent amp(s) I can find at a price point so I can't follow your recommendation.  I typically use an 805 based SET for the upper bass, mids, and tweeters but am using a bridged gainclone presently.  I won't give up any transparency or detail in these areas.  Thanks though for the input.  Any ideas on minimalist active preamps to run the bass section anyone?  Thanks!
lcherepkai
why would an active crossover be the right choice in my situation?
There are a lot of advantages to active biamplification. Passive crossovers are inefficient, so you’ll likely have less distortion using an active x-over. Also, with an active bi-amp setup, any clipping on one amp won’t have any influence over the other.
cleeds--would adding an active crossover, say an NHT X1 or X2, negate the need for an active preamp to increase the gain?  
lcherepkai m
cleeds--would adding an active crossover, say an NHT X1 or X2, negate the need for an active preamp to increase the gain? 
I'm not familiar with those xovers, but you could try it. Personally, I'd never want to forsake using an active preamplifier.