Help deciding which TT

A little background.

I currently have a Rega RP1 w/Ortofon 2M Blue. It seemed great until I added a subwoofer. The sub is exhibiting woofer pumping when attempting to play vinyl. The problem even occurs if I place the needle on a record without the motor running, and then increase the volume. As the volume increases (again, the patter is not moving), the subwoofer (Martin Logan Grotto I) will start to pump. Eventually the sound becomes audible.

That IMO eliminated any motor, or bearing issues.

I've moved my TT to a wall shelf which seemed to have greatly reduced the pumping, but it's still present. I'm at the point where I'm thinking about purchasing a higher quality table. Here are some options I'm considering.

1) Brand new Clearaudio Concept w/ Clearaudio MM $1600
2) Demo Rega RP6 w/Exact Cart (full warranty) $1500
3) Lightly Use VPI Scout JR w/Ortofon 2M Black $1300
4) Used VPI Traveler V2 w/2M Black (200 hrs) $1000

I understand that I may have still have the same issue, but I'm hoping a better table will reduce/eliminate the issue. Any thoughts on the above tables?

"It is acoustic feedback from the sub into the turntable body...bearing...platter...stylus. Put a slab of granite under the TT on the wall shelf."

I have a 30lb two inch thick slab of Maple between the wall shelf and the Rega. The rega sits on top of four Herbies tenderfeet instead of it's normal three stock feet.

The Martin Logan Grotto i subwoofer is the only thing connected to the LFE output on the receiver. The phono preamp is connected to the receivers analog (AUX) input. The only time I've ever used the USB is to connect the preamp to a computer for recording.

I don't think the Rega Mini Fono has the ability to lower the gain on the analog connections. I think the gain control only works with the usb port.
"I don't think the Rega Mini Fono has the ability to lower the gain on the analog connections. I think the gain control only works with the usb port."

You can sometimes control each input on a HT preamp individually. I keep coming back to this gain issue because 5.5 MV seems pretty high. I haven't uses a MM cart in years, so I guess that could be normal for them. The highest output cart I can remember having is a DV 10x5 at 2.5 MV, and you needed to set the phono pre on MM to use it.

Maybe try fooling with the xover on the sub. See if you can set it to have a limit on how low it will go. It may be having a difficult time with really low notes, and that distortion is somehow effecting the system. Also, it wouldn't be a bad idea to try connecting the sub normally, without using the lfe, and any other type of EQ/Room Control processing.
Any possibility to add a subsonic filter? Lots of budget phono Pre amps have them too.
Your current table and the ones you list are all non-suspended subchassis designs. A suspended design might work better in your room.
Some questions that may help the troubleshooters :
- Is your shelf between the speakers or in a corner?
(Placing it halfway along a load-bearing solid wall will minimise the effect)
- How far away is the T/T (& cartridge) from the nearest speaker/subwoofer?
- Is the floor suspended?
- Is the shelf wall load bearing?

One scenario would be to try distancing the T/T and using a longer interconnect to your main amp but since that may involve moving the shelf (or the loudspeakers) I suspect the best WAF solution is another table? (I think you've pretty much resigned yourself to that solution anyway?)

If all else fails a good option would be a suspended subchassis T/T. (Not sure if any of your stated choices are?)
These are often purported to be able to be placed directly on top of a full-range floorstander and still be able to play successfully without interference (albeit not the ideal choice of location!).
Kind regards,