#1
I always see recommendations for 5150/5150ii/6505/6505+. I wanted to see what your favorite amps were that compliments the 5150 sound (like if there are two guitarists in a band and one has a 5150 what amp would sound the best for the other to have in your opinion).

i saw a a band who had a 6505 and a marshal jcm 2000 and that sounded pretty good together. ive never head a dual rec with one but i have been told they sound great together.
#2
I like something like a pissed off Marshall in conjunction with a 6505.

1977 Burny FLG70
2004 EBMM JP6
2016 SE Holcolmb
#3
3120 blends pretty well with a 6534+ (I use the 6534, the other guitarist of my band uses the 3120).

other than that, a dual rec might work well.

I do remeber seeing another local band playing a 6505+ through an emporer 4x12, and a DSL on a marshall 4x12, and in general the guy with the marshal had a pretty bad tone. and then one of the last bands of the night had a 3 ch dual rec and a 6505+ and their tone was jaw dropping.
#5
i have a 5150 mk I and in my previous band the second guitarist had a VHT deliverance 60. fitted pretty nice. but i guess all in all it's the EQ that counts. of both guitarists have a good sound (know how to tune one) everything compliments i guess... it's just a matter of what u want and/or need.

also keep in mind that you can get a certain variety of sounds from a certain amp...so your eq tuning knowledge and imagination are the limit
#7
a dual rec would probably work a bit better because of the headroom, but it should work fine
#8
I don't know if it would be ideal, but it seems like EVERY local metal band in the area (including mine) has one guitarist with a 5150/6505 and the other with a Valveking. Sounds good to me and it's cheap. a Rec would probably sound better though depending on what cab you have.

BUT, I'm sure you already know this, but a good head and a good cab sound WAY better then an amazing head and a crappy cab
I hate my sig