The Tyros 4 has no smooth sound transition; this means that if you change a registration during a song any lingering note from the previous registration will be abruptly cut off. This was one of the things that bugged me most when I had the Tyros 2. One can only hope that Yamaha has fixed this problem in the Tyros 5.
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Korg Kronos 61 and PA3X-Pro76, Roland G-70, BK7-m and Integra 7, Casio PX-5S, Fender Stratocaster with Fralin pickups, Fender Stratocaster with Kinman pickups, vintage Gibson SG standard.