Suggestions please!! --Need to replace vintage Audio Research VT 200 Tube Power Amp

I have owned a Ref 110 and Ref 150. I then placed KT-150s in my Ref 150 which brought it very close to the performance of the Ref 150SE.
The Ref 110 drove Watt Puppy7s and then Sashas. The Ref150 drove Sashas and then Alexia 2s. I test listened in my home Ref 250 monos v the Ref 150 with the Sashas and there was hardly a difference in the power department--virtually unnoticeable to me.
 I now own the Ref 160 monos with Alexia 2s. My take is that the Ref 150 has more than enough power (check out the big power supply) to drive ProAc Response 4s. Although the Ref 160 monos are the best ARC amps I have ever heard, you pay a lot for the extra clarity, power and imaging. Maybe an overall 12-13 percent difference over the Ref 150 with KT150s. IMHO, the Ref 150 with KT150s or the Ref 150SE are the best bang for the buck by far in the ARC line and indeed I cannot say enough about what a blazing bargain they are in the larger amplifier market.
Get a Ref 150 or Ref 150SE. DO NOT get a Ref 110. The difference between the Ref 110 and Ref 150 were substantial. The Ref 150 sounded more powerful and made the Ref 110 sound wispy in comparison. Hope this helps.

What gpgr4blu says makes a lot of sense.  What he did not speak about is the difference the SE upgrade made to the stock Ref 150.  I owned the Ref 150 and had ARC do the SE upgrade.

The SE upgrade is more than just a KT-150 tube drop in.  The SE upgrade also entailed numerous part change-outs.  I did the KT-150 drop-in into my stock Ref 150 and did a lot of listening.  Later, I had the SE upgrade done.  Major and very noticeable improvements across the board.  Well worth the money.

I never heard the Ref 160 so I cannot give you any comments about how the Ref 160 stacks up against the Ref 150SE.  If gpgr4blr says that the Ref 160 is about 12 to 13 percent better than the Ref 150 with KT-150 tubes, I surmise that the Ref 150SE may be closer still to the Ref 160.  

In any case, the Ref 150SE is a terrific amp.  Definitely something to consider.  

BTW, not to throw a spanner into the gears, but at some point you might want to think about upgrading your Ref 2.  Perhaps asking ARC if they still do the MK II upgrade.  

In any case, as far as the front end is concerned, you should call ARC and ask the customer service rep for some suggestions. The late model LS preamps are pretty darn good.

BIF

So I wound up going with the ARC Ref 150SE, and couldn't be happier! Plenty of power, not even remotely an issue, and already an improvement in SQ way before break-in hours.  Thank you all for your "sound" advice, I would have been lost without it!
Take care and stay safe everyone.
Mike

Congrats!!!  Good decision.  I wish you many years of listening pleasure.  

I have some "care and feeding" suggestions.  First, as you now know, the amp is heavy: 75 pounds as a stand-alone; 100 pounds when boxed up.  Consider ordering a bunch of bias resisters from ARC (2 different resisters per tube). They are cheap.  If in the rare case, a KT-150 arcs, you can avoid sending the amp back to ARC for a simple burned resister change-out.  Hopefully, you are close to a tech who can do the job, or if you are handy, you can do it yourself.  But always remember, … there are high voltage touch points all over the place under the hood. So be very careful when fiddling under the hood.

Second, if you don't have a multi-meter with probes, you need to buy one in order to check bias.  I check bias every couple of months.  The KT-150s will drift over time.  And don't get OCD about bias changes.  Bias voltage (65 mV DC on the set tube) will change as line voltage changes.  Don't go nuts about line voltage changes.  Line voltage will change by the hour, especially if home appliances draw heavy amps, e.g., air conditioners, and maybe the washer and dryer.

Hopefully, your amp came with a tiny plastic thiga-ma-giggy screw driver to adjust bias.  If not, I am sure you can buy one from ARC.  Again, … be careful about high voltage. 

Last point … tubes.  ARC charges a fortune for replacement matched KT-150s ($275 per tube).  Kevin Deal did a great job on my last re-tube.  Bias deltas between the set tube and the slave were within 3 or 4 mVs, which is good.  ARC may be a little tighter, but not significantly so.  Upscal Audio charges $127 per tube.  You need to buy matched pairs, preferably matched quads.

I have a question for you.  Which taps have you tried and settled on?  I have switched back and forth between the 4 and 8 ohm taps many times, but have settled on the 8 ohm taps.  FR may be a little tighter on the 4 ohm taps, but for some reason my amp/speaker combo just sounds better off the 8 ohm taps.  That said, FR will fluctuate +/- .8 db off the 8 ohm taps (an Ohm's Law thing), so in a sense, the amp is a bit of a tone control.  Ignore it.  No speaker is 100% flat.  And when you consider the room effects, ... that is another tone control.  John Atkinson measure the FR of the Ref 150 (not SE) here:  stereophile.com/content/audio-research-reference-150-power-amplifier-measurements (www deleted).

If you have any questions, feel free to send me a PM.  I love the Ref 150SE.  It has been a dependable workhorse for many years.

BIF

P.S. -- If and when you think about a preamp upgrade, you will be shocked by the ARC Ref 6.  Amazing!!!