"I hadn't even noticed until now that Mercury is in strong aspect to the MC and Venus too (MC at 21 Pisces, Venus 23 Cap, Mercury, 24 Scorpio)"
Yes, this was one of my main reasons for choosing the chart as well.
It's not just Venus alone but a good dose of Mercury / Venus that would be necessary for musical ability - and the strong Saturn is important, imo, overcoming both planets (by sextile and trine, not a fussy square) which supports and gives mastery to the planets; repetition and practice = mastery.
Venus being the bound ruler for both ASC/ASC ruler (aka sect Light), the Moon, and Venus so strongly advancing on an angle and having dignity at both ASC and MC (as stated in my response below) are the other main reasons.
I did point out that Mercury strongly trines MC, and, I think rather importantly, is at the midpoint of (and so receives a strong *degree-based* sextile from both the planets on angles) Venus and Saturn.
I think that trine - Jupiter overcoming Venus, is rather important too.
Venus, planet most important for artistry, is in a stake and is strongly advancing on an angle (DC). She has dignity at both the MC and ASC, and is also overcome by Jupiter (and Saturn, her dispositor) by a very benefic trine!
The ruler of the Ascendant, the Moon, sees the Ascendant by a strong trine from the 5th. In a way this indicates that the person sees what he wants and how to pursue it, or, simply, what is important in the life are 5th matters: creativity, etc.
The ASC and the Moon are also in the bound of Venus.
Saturn, in the whole sign 3rd place (communicating something), is also very strongly advancing on an angle (IC) and is the domicile lord of Venus, in addition to dispositing to the other planet that I believe is important for musical ability, Mercury.
Mercury, also in 5th, trines the MC strongly, and actually sits at the nearly exact midpoint of the two major planets advancing on angles, Venus and Saturn. To me, this may be about giving form via a kind of communication, or through the hands, to an artistic endeavor or practice (VE SA).
I had a lot of fun. I look forward to more of these! Thanks.