The gap is too small for even small fingers, but runs all the way around so it adds up to a reasonably large opening.
It sounds great. It is based on the Decware SE84CS, but uses premium parts. The high primary of the output transformers reduces output in exchange for improved linearity. It puts out a bit more than two watts a channel, and requires high efficiency/sensitivity speakers. My primary speakers are Klipsch La Scala. It works well with Klipsch Heresy as well. It really needs 95 DB/W/M and above.