Which would be preferable, an older Audio Research Corp. VT130 or a newer SS Rotel 1552?

I agree with others that if you aren't loving the sound of your setup, speakers might be the best place to start. But maybe you already know that you love the 805, and you've heard them sound better than what you currently hear.

If that is the case I would say go for the Audio Research but only if you are prepared for the potential hassle involved. Buying an older high-end piece like that is kind of similar to buying an older high-performance vehicle. Both can be rewarding but also both can get expensive when it comes to repairs or maintenance. In this analogy the AR would be an older German performance vehicle. Great to drive but likely expensive to maintain. The Rotel would be a newer Lexus or Acura. Still quality overall, exchanging performance and character for reliability and low cost of maintenance. 

Easy for me. I would go for the Audio Research VT130. It will sound much more natural, organic and musical. The Rotel is punchy, accurate and neutral... but not as musical and organic. 

I agree with the speakers. B&W's are the issue. Get a more efficient speaker and drive with lower power tubes. That VT130 is old, heavy, and expensive to ship when it needs work. If it's clean or been redone maybe but most of the stuff for sale these days is overpriced and beat up. 

+1 freediver

Always remember in audio everything is a trade off.