I have experimented a lot with pro audio studio monitors .. ATC, Genelec , KrK etc..
ATC and Genelec do some stunning stuff .. I listened to a Genelec based system the other day and was truly blown away .. their top of the range speakers(I think it was the 1000 or 8000 models) and twin Genelec subs with their room correction..
Krk VXT8 + their 12sho sub for round $4000 is an exceptional system too for the money ..
Prior to my giya G1's , I used meridian DSP6000's and 2 SVS sb13 ultra subs , bought the whole lot for $5000 2nd hand.. it took the G1's to beat it at more than 10x the price..
Given that you've found your bliss with a pair of Giyas, it's not surprising that you like pro monitor/sub systems. Given that he's into tubes and vintage horns, it's not surprising that David hasn't heard anything from the pro monitor world that appeals to him. These represent very different design approaches resulting in very different strengths and weaknesses. And that gap between what represents a "giant" makes it pretty difficult to ID giant killers.
Tim