The best integrated amp for Klipsch Heresy

NAD has been a good match for the Heresey. I bet Creek sounds good too. But, if it were me, I would try a nice tubed unit from Jolida. The Heresey's are famous for being efficient so you dont need much power.

This review of the Rega Brio-R matched the amp with Klipsch Heresey IIIs to good effect. It also has a very low noise floor, which is essential for an amp powering very sensitive speakers. The PrimaLuna One mentioned in the review sounds like it would be a good match. And another affordable integrated with a freakishly low noise floor is the Marantz PM8004. The s/n spec on the amp section is 125 dB.

Any of the Cayin tube units will give you great sound, and a great value.

Been thinking of a older McIntosh amp say MA6300 or MA6450 matched to my B&O 4200 with a MMC 20CL driving my Heresey ll could this be a match made in heaven??

Again - the Heresys are extremely efficient which gives you a great opportunity to play around with some low-watt tube amps including but not limited to SETs, which will give a far more detailed, engaging and magical sound than any hulking solid-state McIntosh will give you - especially if you're willing to shell out what an MA6300 would cost.

Mating a SS Mac amp with Heresys is like mating King Kong with Fay Wray.

Look into Almarro, Decware, Miniwatt, Bottlehead, or the vintage Scott that was mentioned, a nice Eico HF-81, etc.