Is there a point of diminished returns with amps and Harbeth 30.1s?

@dhcod  I have owned the M30.1s for a few months now, and I can certainly relate to why people fall in love with them. I have them set up in my home office driven by Raven Audio Blackhawk. A few weeks ago, I temporarily moved them to my media room (20x15) and hooked them up to the Luxman 590AXII to see how they perform. Let me tell you, it was a revelation! They actually sounded better than Sonus Faber Olympica 2 (now sold) driven by the same Luxman. They had a blacker background, even better midrange, and that 'singer in your room' feeling was more enhanced. The SF sounded thin by comparison, although it had more bass slam to be fair.

So based on my experience, the 30.1s will most definitely scale with amplification up to $10k. Anything north of 10k, I'm not sure ... yet :)

Suncoast audio has a new YouTube video up of the M30s being driven by Luxman’s new limited edition Integrated, and it sounds fabulous.  I understand the new integrated amp is similar to the 590.  Luxman and Harbeth are a great match.  I have the M40s with Luxman separates and love the combo.  But I’ve never heard Herron, so I couldn’t say if it would be an upgrade.

+1 for a new cartidge.  An Audio Technica AT ART9 XI for example.  

Had one. Hated it. Exactly the opposite of the sound I enjoy but that’s just my ears.

I know you are asking about amps, but IMO, contrary to Alan Shaw's opinion, speaker cables make a big difference.  I've owned the M30s, SHL5s and P3s and I've found the right speaker cables to improve the sonics significantly.  I don't know what you're using now, but if you have to move the speakers often, I would see if the Cable Company has any more Audience AU24 show demos at 1/2 price.  Excellent sound and very easy to work with.  I also love Purist, but they are not the cables to be moving around on a regular basis.  Not that you can't, but they are kind of bulky compared to Audience.