It's a VW Beatle with a Porsche engine - loud and the sound is ok. I'm more after Hifi-Sounding units, and there are a few out there which plays the M90 on the wall.
Better sounding units (than M90): - Grundig Party Center 2000 - Rotel RMP 10 - Telefunken Hifi Studio M1 - Telefunken HP 800 hifi - Uher power port - Yamaha YST- and AST-systems - ... just a few of a longer list I could write here. But I love my M90, because it's a part of the boombox-history, and for me as a boombox-collector a must have. I also own the GF-777, M70, Sharp VZ-2000 and 2500, Marantz PMS 7000, Fisher PH490, Technics SA-05, ... just because I love the look of them, not because they are great sounding units. There are so many other, better sounding bboxes out there ...
I just bought a JVC PC-X 1000, the biggest PC-unit ever built. It's on the way to me, so I can't tell you how this one sounds. I already got a headunit with missing speakers, but I can tell you that this one is the mother of all Kabooms - the built in subwoofer sounds very brutal, so I can't wait for the first soundcheck ... I will tell you about it ...
Here is a pair that is well comented of The Panasonic RX A5 & the A2 