Best amplifier and preamp for klipsch heresy 3

A low- to mid-wattage vintage Audio Research tube amp (Maybe a D76 or D79) with an Audio Research tube preamp (SP-6, SP-9, SP-10) would be a good combination with the Heresy III. 

If you really want to try something interesting, try a Dynaco ST-70 or a pari of Dynaco Mk III amps.  Stock, the sound can be very nice.  Modified, these can be quite good.  With the right tube complement  Both have more than enough power for the Heresy's.  VERY VINTAGE.

Have you considered Primaluna. I auditioned the H3's with my Primaluna HP integrated and was sold on the combo. I did not hear that dull sound you mentioned. A very nice match IMO.

A friend of mine has a set of older Heresy's (mid 80s). Though the IIIs are somewhat better, they are very similar to the originals as I understand. We have driven his version to loudness levels beyond what was comfortable with an NAD 326BEE. That said I believe these speakers are best served by the the more classic tube sound (EL34 type). Regarding a balance between sound quality and budget, I don't believe these speakers command amplification beyond ~$2000 price point.

My friend has driven them with a current version of the Dynaco ST-70 and said they sounded wonderful (I was not present). However, we also plan on driving them with an original version of this amp I had recently refurbished. I will have to get back to everyone on this.

If I owned these speakers I would choose to drive them with a tube integrated. I would consider Jolida or Prima Luna 35wpc integrateds. If going separates and wanted SS drive, I would pair a SS amp with a tube pre. The Odyssey would be a good choice however supplies more power than needed. I don't consider this a problem however as long as one can use the pre at appropriate gain levels.

Ive ran bigger klipsch with Odyssey amplifiers , not because they needed it, just had them so hooked it up.  I would go that route, when you get sick of the klipsch horn sound you will have an amplifier capable of driving about any speaker.   To get the classic klipsch sound you should be looking at low power tube amplifiers , 2a3c would be on my short list.