On one of my Yamaha seminars, I've seen a Tyros4 with the cover off...very little wasted space inside.
I suspect the Tyros5-61 would be similar.
Check out post #373434 earlier in this thread. The picture (which is of the Tyros5-76) is considered to be legit.
Ian
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Yamaha Tyros4, Yamaha MS-60S Powered Monitors(2), Yamaha CS-01, Yamaha TQ-5, Yamaha PSR-S775.