garrard vs clearaudio innovation

IF there is low frequency rumble, that fact that you don't have conventional woofers will only save you from having to observe the cone dance that might otherwise result.  However, the rumble would still eat up amplifier energy and possibly cause distortion in upper frequencies.  I say "if".  I don't necessarily agree that the 301/401 cannot be modified to eliminate or at least ameliorate that problem, without going all the way to the Artisan Fidelity set of solutions.

Instead of Artisan Fidelity, here’s what you can do for less money:

• 1. AudioSilente idler - $110
• 2. PAC 20mm oversize aluminum platter from CTC in UK - $750.
• 3. SPH bearing - $250

These 3 options will take your 301/401 to the next level. Huge improvement.
The SPH bearing reduces wow and flutter from 0.14% to 0.06%.

All I am saying is that if there is any low frequency rumble I do not detect it in my listening sessions.

And yea I am from the days of receivers from the 70,s where the rumble and the hi filter were de rigueur.

My fathers Rek O Kut Turntable not only rumbled but it fed back like crazy. On the HH Scott Preamp the rumble filter was always turned on.
He had a custom cabinet made for the whole system and looking back the turntable was mounted poorly. It looked nice though and was hidden under a hinged cover. The end result was that he got a bunch of prerecorded tapes and listened mostly to his Ampex and what a wonderful machine that was. Instead of scratches you got hiss. No dolby back then and the prerecorded tapes ran at 7.5 ips. Other than that the sound was wonderful. I was in charge of demagnetizing it once a month.
Anyway, many modern subwoofers have room correction with equalization to push the driver as low as feasible. If there is any noise below 30 Hz it can get magnified as much as 10 dB. So you can see what turntable rumble might cause. My system is digitally rolled off at 80 dB/Oct below 18  Hz. If I remove the filter and play a dead groove the woofers will flap a bit even with the SOTA. When I turn the filter on the woofers go almost dead in the water. 
Uberwaltz, if you can look closely at your woofer membrane and play a dead groove with the volume up you will see it flapping back and forth. Shine a flashlight in there! I've never seen one strike the magnets but I suppose with enough power it could happen. Anyway because the Maggie is a dipole it has a lot of trouble producing sound below 30 Hz. It just cancels out. But the membrane is still flapping which is why I really like to see subwoofers and high pass filters used with Maggies. You have to use two subs and cross at 100 Hz or even a little above. I have used JL Audio Subs under Maggies with great results. Of course if you only listen to digital files none of this matters but then what are you doing on this thread:)
Lewm I think you are basically right about wasted energy and distortion.
You can make a bunch of improvements to those old tables and they are serious metal having been designed for commercial use but you still have two more bearings, the idler wheel itself and the capstan mechanically connected to the platter. In a belt drive you only have the spindle. Even assuming that all the mechanical part were as good as reasonably attainable the idler wheel table is still going to make more noise than an equally machined belt drive. Can you make an idler wheel table quiet enough to function well with corrected sub woofers? I don not know. I can only say that I have not seen it done yet but it is not impossible but probably very expensive:) 

I had a Clearaudio Innovation on a cheap rack (Lovan) on suspended wood floor (but much more sturdy than that of a typical residence, which are impossibly flimsy), and I would experience nasty woofer flapping at times. It was very easy to see on my Tannoy’s big 15" drivers. I upgraded to a high-end rack (CMS Maxxum) and Clearaudio Master Innovation at the same time. No visible woofer flapping at all since then, not even a tiny bit. No more feedback issues of any kind. I listen at loud volumes, too. Sounds wonderful. I think these Clearaudio tables are capable of being extraordinarily quiet, but you must provide them a proper platform.