Where to go next with the turntable

@traudio ,

Which is not a whole lot. The lowest note on a 4 string bass guitar is 40 Hz. 

Play a 20 or 30 Hz test tone, turn the volume up and put your hand on the panel. You will feel it vibrating. That vibrating distorts everything else. If you only listen to string quartets at low volumes it does not matter. If you use a turntable even just the records themselves generate rumble exacerbating the problem. A flat response does not necessarily mean a detailed performance. A system can do a short sine sweep beautifully and sound terrible. You are familiar with MiniDSP. The SHD is $1500 with the UMIK 2 and it will do everything you need including a digital two way subwoofer crossover which will allow you to take the crossover point up, cleaning up the Maggies. MiniDSP also makes a stand along crossover.

If the Sota Sapphire is too big a bite I encourage you to look at the Thorens TD 1600.   

mijostyn

I use an Hegel H390 integrated amp. No way to use this DSP thing without changing my gear, or using my integrated as an amp only.
Sticking a $1300 digital pre-amp in front of my system, I'm afraid would degrade the sound in spite of improving the bass. 

Might look at the Thorens

This is tough.  I have owned Rega, Thorens, Linn, ProJect, AVM, VPI, Gold Note and SME tables.  My experience is that low mass tables like Rega are always going to leave a smidge to be desired in terms of bass.  Moving up may not give your more of what you are looking for.  

Linn certainly requires maintenance.  Thorens requires less tweaking but is not immune.  I feel the same way about VPI arms as you.  The least amount of maintenance I have seen on a table is SME.  They are very much set it and forget it.  You might find a Model 6 or 12 will be low maintenance and deliver what you want in terms of bottom end.  Big issue is the price as they are not inexpensive.  Depending on the arm these are $8k to $13.9K options.  

Gold Note and AVM are less expensive and higher mass alternatives.  They could be interesting choices.  

Full disclosure, I am a Thorens, Gold Note, AVM and SME dealer.  

Turntables are a very personal thing. Again like everything in Audio you can listen to opinions, and at the end of the day, it is what the equipment sounds like in your listening space. My main table is a Marantz TT-15S1 Which is a clear audio table to be honest. I spent some money on a Jeff Spall Series six tonearm from England, With good quality toner cable. I then bought a Goldring Ethos MC cart. At present I am looking to upgrade to a new Dynavector Te Kaitora Rua MC Cartridge. After speaking to the tone are maker, he assures me that his tone arm and the new Dynavector cart are a great match. At current, my TT and phono stage combo are killer. Incredible detail and full range of frequency.