A lot of songs have a really bad flutter/warbling sound over them.  Does spotify transcode low bitrate MP3 or other codecs to OGG?  I've been paying for premium for a few years, but I'm getting frustrated with how much terrible sounding music there is.

This isn't simply a matter of bitrate.  These are clearly compression artifacts that shouldn't be there even in a low bandwidth stream.  I encode all of my CDs to OGG q5 or q6 so I can fit more on my portable player, and the same songs in my own collection sound very good in comparison.

Let's assume for the sake of this discussion that I know a lot about digital audio and neither me, my computers, or audio equipment is at fault. I've listened on several computers.  They're all set to "High quality", I have normalization turned off, and I'm listening through good headphones with a variety of audio interfaces, and I know how to set things up.

I hate to sound as negative as I'm sure this looks, but I'm wondering if I should just dump my subscription, or if there's any explanation or plans to improve things?