Another vote for 4v. Sweet sounding with that slight HF boost, great if relatively close, say 50-75 feet, for a big room back by board love my 41v.
Is there a sonic difference between the MK4 and the MK4V ?
Yes - mk4v has a HF bump and then tapers off completely at inaudible frequencies (above 18khz) - mk4 is flat and doesn't taper off
Some prefer the mk4v sound - I do not - slightly too bright IMO but the main issue I had with them was they seemed to be hard to get to be pointed just right to get killer sound consistently - I did pull some great tapes with the mk4v but my best tapes have come from the mk4 and mk41
I have owned mk21, mk4, mk4v, mk41, mk5, and mk8 pairs over the years - I prefer the versitility of the mk4 in general, the mk5 and mk41 are close seconds