I did.
It sounds fundamentally the same as it does in DAC/amp form. But you need to run it at, essentially, it’s maximum volume when using it to drive another amp, and that’s not a configuration I am particularly fond of - since you’re amping an amp, that’s operating in at its limits … noise and all. There’s a specific discussion of the issues regarding amping-amps starting here.
Ages ago I did a comparison, and extensive review, of a bunch of portable DAC/amps, both as DAC/amps and also just as DACs. You should be able to find what you need there, but bear in mind its spread over several posts, so don’t just stop on the first one.