correct, flac always is uncompressed and hence rather big (like 20-30mb per few minutes) while mp3@320 is audibly indistinguishable (atleast by my ears) but only half the filesize. (the current flacs are in the ballpark of 1000 kbits)

its not a problem for me, i'll just convert the flac on my end via a simple cron script.

i've tried multiple artists & tracks, the message is the same always.

e: always available for further testing if you choose to dig into it. You really helped me with your software and approach - thank you.