You have made my point. If you mix with aberrant speakers, then when you play on decent speakers, the faulty sound of the monitors is revealed.
This week an engineer did a mix and recording all weekend. The monitors were those Ymahas. Then came here to listen to his work. It all sounds awful to me anyway, but he seemed happy.
What I notice is that on all this type of recording is that there is never any depth of field, and it always sounds more like mono than stereo. Not only that when you look at it on the phase scope, it actually is more like mono than stereo. It all revolves round these pop industry techniques. You can't put up a bunch of mics, and use pan pots to create your sound field. Unless you use isolation booths, which seem to have been out of fashion for some time, then there is so much bleed between the mics, it is essentially more like a mono than a stereo recording. This is why you can not use an upmixer with music from the pop rock domain, as it all pretty much goes to the center channel, unless you use center spread.
Whereas in classical recordings, the sound field is from distant mics, and I note the Decca tree and variants are becoming increasingly common. That way the upmixers work wonderfully well and you get a wide deep sound stage with center spread off. On the phase scope it looks like stereo, which it is.
So, I suppose it does not matter how you monitor it, as it will always sound awful, as it is universally miss engineered from the ground up.
