what amps/subwoofers are you using for Magnepan LRS?

When I had Maggie 3.5Rs I tried several class D, but that was when class D wasn’t what it is today. I would have loved to hear the 3.5Rs with my recently purchased Ric Schultz EVS1200, which is based on the newest IcePower 600w modules. Betting you would love it too.

A real bargain at ~ $2400 with money back guarantee. How can you lose?

Assuming most panel speakers thrive on current Coda Amplifiers might be a sensibly priced locally produced and serviced candidate.

Multiple smaller sealed subwoofers Crawl Tested locations dramatically reduced my rooms modes. 
If the goal with your subwoofers is to match your main speakers or any future speakers sonic presentation through the crossover region you'll need to find processing that includes auto/manual parametric frequency, slope, Q, and gain.
Adjusting variable phase and a hard crossover frequency forces you to reduce the subs gain just to get a small sense of integration matching.
If satisfied you'll save money and have no idea what your missing.   

When attempting Vandersteen subwoofers Make sure your choice of an integrated has a Preamp out and a Main in for use of a High Pass filter or just use separate Preamp and power amp. In order to achieve this bi-amping resulting in an even better Transition for LRS,.7 and other speakers. One of the main advantages when hooking subs up at speaker level instead of line-level tube preamps are not driving into a less desirable low input impedance. The use of a high pass filter as in Vandersteen Sub 3 and prior model 2WQs use, in particular, allows the main speaker's modulation distortion to be lowered, heavy lifting of your main amplifier relieved dramatically Improving Clarity and transparency of the whole system.
The sub-three features 11 analog EQ pots clean up the in-room bass response and done without any DPS processor, The same analog system is also used in the more expensive Vandersteen Quatros, Five series, and Sevens and has now trickled down.
best JohnnyR
Vandersteen Dealer