Well, by right, anything you buy overseas more than $500 will have to declare and pay GST upon returning to Singapore. But usually for smaller items most people just won't bother declaring lar. But for BNIB speakers hard to avoid Customs so I guess you need to pay the GST upon returning.
Checked those Tokyo shops, seems like Fujiya Avic is selling the Menuet SE the cheapest
https://www.fujiya-avic.co.jp/shop/g/g200000050547/
After factoring in GST, still cheaper than $2K. Anyway, can try to ask E77 to price match first. Usually if you go down in person to their showroom they would give 10% off their listed price. Maybe if you show them the Japan price they might be willing to go down further.
You listened to the ATC at Chinatown? When I went down to listen to it, they paired it with Rockna Wavelight and the big Line Magnetic. It was quite aggressive sounding, but after changing the Dac to Aqua La Scala more rounded and pleasing. So I think it was the DAC.