This, because...
...this.
The device label TFs seem to me to be TFs first, with the functional device aspect as their 'gimmick'. Bassimus Prime there 1: doesn't transform, 2: is too large to be 'played with', and 3: has it's primary function as speaker rather than plaything. It's a speaker shaped like Optimus Prime, rather than a toy with a speaker component like Music Label Convoy.
That said, I could go for something like that if they came in Blaster and Soundwave/Soundblaster styles. Maybe a surround sound setup with some of the mini-cassettes for smaller speakers.