That is the best quality of an ogg audio. It is lossy. Mostly in the mid / high frequency domain you will notice some differences.
You can perhaps try a -3 or 0 db, depending on your audio content. This provides you better quality either way.
That’s set for compatibility reasons, you will find the -3db setting in the Config/Windows/WindowsEngine.ini (or mac/macengine.ini)
Yes i’ve had strange issues with 44k audio, but since i use 48k everything seems ok. Not sure about the stereo image problem tho, it could be related to the ogg vorbis implementation in engine.