Have recently purchased NHT 3.3 from an audiogoner

Have recently purchased NHT 3.3 from an audiogoner (or is it audiogonite). Auditioned these 8 years or so ago, always remember how great they sounded in a Chicago audio store playing Dark Side of The Moon. I now feel fortunate to own a pair set up in a 2-channel (mostly) and 5.1 system with NHT AC2’s and NHT 1.5 rears and NHT sub 2. For the first week drove them with Adcom’s gfa 5500 2x200watt @ 8 ohms using AQ c4 biwired speaker cables and Monster interconnects through a Yamaha rxv 2200 ht receiver 5x100watts as a preamp. My source components are Yamaha carousel (awwwful) cd player and a 25-year-old TT from Scott. Not bad results especially considering the front end stuff. But this system needs help!!! Mid’s were just ok but not very defined (muddy) and the vocals seemed recessed. Bass was very nice and the highs not as bad as the mid’s. Just for kicks I
Bi-amped them with the Adcom for the uppers and two front channels from the 100-watt htr for the bass. This helped the upper region a lot but the bass was now terrible with drastic problems with the gain of the two different amps. Using the sub to help the lower regions this has the best results so far. I would like to get the amplification up to par before I work on the front-end stuff. I don’t think even at 200watts of my Adcom amp for the mid’s and tweets has opened up that region as much as it should have or could have. I’m considering the Adcom 565 mono blocks 300watts @ 8 ohms and the Adcom 5500 for the bass. I don’t have 2 main outputs on my htr and am not sure of the results of using a Y connector. Should I consider an altogether different amp and not try to bi amp???? I have read a post of a NHT 3a sub amp but could not find any info on it. My guess is it’s a class D amp and not sure that it’s for me or the 3.3’s. I'm thinking of $1000.00 to $1500.00 for upgrading the amp/amps. I enjoy listening to R & B, R and R and little jazz. Any help would be greatly appreciated. Thanks T. J.