Amp - preamp or integrated

For your budget, I’d stay with the rogue unless:
1: you need more power. Do you have the KT120’s? Get the 120’s
2: Do you need to tighten up the bass?
3: Do you want to go SS?
I had the same amp with the kt120’s and it was a great amp until I changed speakers and the bass wasn’t controlled enough for me. I did change the phono and preamp section tubes and switched the internal wire for 4 ohm speakers which helped in the bass.
I went with the Hegel integrated amp which had 250 watts, neutral sounding and tightened up the bass. This had the internal dac which I did not use. You can pick up a Hegel 300 or 360 for around $3000 which are fantastic integrated amps.
Since upgrading to larger speakers, I went to separates but the preamp alone cost more than the Hegel, and the amp was 2x the cost of the preamp plus cost of cables. 

I don't believe separates are competitive sonically at the price level you suggest. I'd rather listen to a Luxman 5550AX II than any system with a preamp selling for less than $3k. I'd rather have an Ayre EX-8 than any separates available for $8k. Power transformers and chassis are a much higher portion of costs than they were back in the eighties. Also, the best engineers have learned how to put pre and power amp in the same chassis without overwhelming noise issues.

I got a pair of used Rogue m150 monoblocks and a NAD preamp/tuner for a total of  $2600 and haven't looked back, system sounds amazing 

I also own a Rogue Cronus Magnum II (with which I'm very happy). The CMII does have 2 outputs (L/R) which can be used to drive a powered sub. They are the variable outputs.

So far I had my Vandys 2 sig for over 4 yrs. It seems im ready for a change or at least would be open to listen to others. Heard good things about the magnepans. They seem to require a good source or current which my Rogue CM did not supplied. So my dilemma is how much of my current equipment will I change.

Very few amps, regardless of price, are as musical as the CMII. I actually prefer the CMII to their ST-100 and Pharaoh integrated.

If you're interested in the magneplanar or electrostatic sound, but don't want any of the drawbacks (smeared - unrealistic imaging, poor bass extension, current sucking impedance, narrow sweet spot, and limited SPL ability) then look into Spatial Audio's open baffle speakers.