Hi, Joe: Yep, I have the CODA 15.0 and love it. I will be happy to give you more information via phone if my comments here don't suffice. Try to send me a private message if that is the case, and I'll email you my phone number. First, I have 4-ohm speakers (Tyler Woodmeres), which require the grunt of a high-current amp to sound their best. The 15.0 was specifically designed to run this type of low-impedance speaker, which pays dividends for those of us living in that scenario. The VAC Sig 2a was on my short list, but I ended up with a Purity Audio Designs tube preamp instead (also very highly regarded). So, my electronics are in line with your potential scenario.
This amplifier has NO weaknesses that I can detect, and my system is quite revealing. I could list a dozen positive adjectives right off the bat, and they would all be appropriate. No one or two or three things stand out with the sonics; each area is as strong as the others. It is powerful, sweet, has all the finesse AND imaging that you would wish for. Instruments are palpable and immediate (if the recording contains it). And all the time, it sounds like music (not hi-fi). My musical test track is pretty grueling, and, among the more difficult passages are complex classical, which can convey a huge shift in dynamic range in an instant, and in the next instant, shift from a full-on orchestral battering to the airiest and most delicate sound of flute and harp. This amp doesn't care..... it delivers whatever I throw at it and doesn't flinch.
I am familiar with the VAC sound, and I think the 15.0 will mate with it very well. Both are sweet, full and liquid sounding. I think you will be more than satisfied with the imaging, too. I have read that high-powered Class A delivers excellent imaging, and I can only nod my head, based upon my results. Stage width, depth, air surrounding individual instruments, layering of instruments in a group, different textures, all of it is there in the highest sonic quality I could hope for. With an expensive tube preamp, you certainly don't want to lose imaging potential with an amp, and solid state might make some folks shake in their boots for fear that they might lose imaging potential. But I am extremely satisfied and could not ask for better. I hope this was helpful.
Ren Tilden/Winter Park, Florida