Do Harbeth speakers really need a 4000 damping factor?

The answer is no, 240 is plenty.

Your amp is not "lowly".

My 40.3XDs are shared as mains between a T+A integrated and a Yamaha RX3080 AVR. I often stream SXM radio from the Yamaha for casual listening and they sound surprisingly good. 

Prior to the 40's, I did the same with 30.2 XDs - very enjoyable.

The stands matter, as do cables. I've use Ton Trager, but if you can build something similar from hardwood go for it, but get rid of metal frames and glass.

Buy some decent speaker cables, for example from Frank at Signal Cable. They are not expensive - I own the entry level cables and have compared them with my Acoustic Zen Hologram II and the are damn good for the money.

Then, maybe find a used Hegel 590 or similar if budget allows. 

PrimaLuna's EVO 400 power amp has a damping factor of 7.  It's their most powerful pure tube amp ever.

The Crown Studio Reference II has a factor of >20,000.

Damping factor is an amplifier measurement.  It is 8 divided by the output impedance of the amp.  Almost all solid state amps have an output impedance so low that the resulting damping factor is WAY in excess of anything meaningful as to the sound; it is largely an irrelevant specification.  The exception is tube amps which tend to have a much higher output impedance, and therefore, a lower damping factor.  There are some amps with output impedance of 2 ohms or so, for a damping factor of 4.  These amps tend to work best with speakers with high and flat impedance curves; with lower impedance speakers, the frequency response will be affected.  Tube amp manufacturers cannot easily reduce output impedance to increase damping factor, anything done for this purpose, such as increasing the turn ratio of the output transformer, will compromise the sound.  That is why speaker matching to some tube amps can be trickier.  

Maybe I’m wrong, but I believe that Dampening factors have very little to do with what brand of speakers you own.

I tried my 30.1's with an A21, a Class D Audio SDS 470C, and ARC 150SE - but they sounded best with my Hegel H590 - greater clarity and detail resolution.  May have been my imagination... but... that's how it seemed to me.

Membrane motion braking current (Lenz law) passes thru speaker, wire, amplifier's output and the other wire. Would adding 0,002ohm (DF=4000) instead of 0.02ohm (DF=400) to speaker impedance make it sound different (damp/brake better)?   Even if we assume 4ohm at low frequencies of 6ohm nominal impedance (1kHz) speaker, we get 4.002ohm vs 4.02ohm.  As long as DF is decent (>20) it should be fine IMHO.

I read that "Harbeth likes to demo with Hegel" (and Sugden?) 

These are 2 very different sounding amps. I've never heard a Hegel I like, even with Harbeth 30's and 7C's. I haven't heard Sugden on Harbeth but I haven't heard an A21SE sound bad on anything...though I'm sure there's a few.

@ahal1

You are aware that Harbeth shows with Hegel, right?

I very much doubt they would choose to do so unless they perceived a significant sonic benefit. Whether Harbeths require high damping factor amplification I can’t say.

I can say that when I switched from Well Majestic integrated with damping factor of 200 to Hegel H390, my Silverline monitors "came alive" in a way I’d never heard. That was a dramatic demonstration of the importance of proper speaker/amp matching. Needless to say, YMMV. 

If you have the ability to build wooden stands, take a look at the Tontrager stands. People rave about them and they shouldn’t be very hard to knock up for anyone with decent woodworking skills. But don’t underestimate the differences a good stand makes to influence the sound  

I have the 7XD with a Leben 300XS and a Supernait 3. They both present wildly different characteristics. The Leben is a holdover from a different speaker and it sounds beautiful at low volumes but doesn't present a soundstage or have bass anything the the Supernait. If I were to ever get a tube amp with these I'd look above 40 WPC, but again that varies wildly with listening preferences and transformers, etc. 

I don't know anything about the Yamaha amp you mention but in my experience you get what you pay for. As far as damping factor I'd say 4000 is a bit over the top and not needed for the 7. Never hears a Hegel amp either.

@ahal1 No, and no loudspeaker ever made does.

All competently designed amps of low noise and distortion will sound alike.

Is that you Mr Hirsch?

"No idea if any of this will be audible,"

Of course it will be.

I am using the speakers with open metal frame (3 columns, glass top with rubber bumpers - inexpensive) and cheap speaker wires. I intend to change the wires this weekend to see if it affect the sounds and I plan to build wood open frame stands... No idea if any of this will be audible,

I’ve heard them with tube amps and they sounded good.  I don’t know the DF of these amps, but I would be surprised if any was much above 8 or so.

I’ve owned several Harbeth models and, while they are very electronics tolerant, I’ve found more difference in the stands and the interface between the stand and the speakers. For my taste, open-frame metal stands sounded best, or at least using a hard interface like casino chips between the stand and the speaker, as opposed to blu tak. But you should experiment with that. They will also respond to better amplification and sources as well. What stands are you using?  

"Do Harbeth speakers really need a 4000 damping factor?"

No! I use tube amps with a low damping factor of 20 with my Harbeths. I          doubt getting an amp with a 4000 damping factor will improve anything!

All competently designed amps of low noise and distortion will sound alike. Since amps look different the Mind believes they sound different. Remove sight and sound differences vanish.