Help me understand how to optimize bass on the Zu Definition Mk IV

I am a longtime owner of Zu Definition Mk1.5 speakers and recently also bought a pair of Definition Mk4's. I based this decision partly on the reviews / feedback posted here on Audiogon in various threads by members such as 213cobra, gsm18439, spiritofmusic and others. I'm really hoping some of you Mk4 owners can chime in and help me out here!

Basically, my issue is that I found the Mk1.5's put out incredibly deep and impactful bass, especially with some of the music I love, like R&B and reggae. And this was with the bass amplitude knob at 12 or 1 o'clock. However, after setting up my new Mk4's, I find the bass underwhelming and anemic, even after fiddling around with various settings and with the volume and PEQ cranked. I have them on spikes into bases on a hardwood floor, with about a 1.5" gap on the bottom. What am I missing here?? Based on the reviews I read, I was expected the bass to equal or exceed the lowly 1.5's. 

Thanks so much in advance for any helpful advice! 

Request ground posts for Sean when he looks at yr amp modules.

I'm sure you'll like the Gaias footers, some mileage there.

The other thing to say David is that eight 10" woofers versus two 12" was always going to present a difference, esp rear facing versus down firing.

I think you need to approach the 4 as a different spkr to the 1.5, blank canvas approach on set up.
Very true, Marc, I'll start from square one with setup once the amps are back. I really appreciate all the help you and Phil have given me here. David
My pleasure David, I hope it helps. I've been masochistically flying the Zu flag for 6 long years on What's Best Forum, mainly receiving brickbats in return LOL - so, its great to try and help by conversing with a fan of the brand.

Certainly I'm sure Sean and Phil can bang their heads together and get you in the right direction.

Be patient. I have been, for 11 years now LOL.
If I can get detailed answers to the questions I raised a few posts back, I might have more suggestions. -Phil
Hi Phil, 

Here's some answers to the questions you posed:

-- no cable TV in my sources
-- no balanced / XLR cables
-- preamp is a Cary SLP-98 with integrated tube phono stage, no SUT
-- no ground lift switches on any components
-- no passive components
-- cartridge is a Clearaudio Virtuoso v2 ebony, tonearm is a VPI JMW-9
-- there is a lamp situated above the turntable, which was causing buzz when turned on, but that was mostly eliminated by running a ground to the turntable and then preamp. The lamp is off when listening anyway. No other power supplies near the turntable. 

Interestingly, Sean sent me this response about grounding the sub amps in the Definition (I'm sure he wouldn't mind me posting this): "When I rebuild the amps I float the audio ground, that is one of the benefits of the transformer. Another thing I do is to better float the AC transform, much of the hum you notice is coming from the mechanical singing of the AC transform, the power supply is linear so it’s a big piece of the kit in size and mechanical effect. Things should be much quieter when you get them back."