Hi there,
before you point me to the search, I'm not looking for any kind of app, hear me out

What I'm looking for is a program that presents a front-end for the various En-/Decoding plugins out there (lame, mpc, FLAC, ape, ogg, etc.)
It must be capable of converting between those formats, which includes batch-conversions of various files while keeping the Tags
Also, I need to be able to edit the Tags and apply them to a bunch of files, not just single ones
The most important thing I need is to be able to tweak encoder. I'm sick of frontends offering me 3 fuzzy settings of bitrate and nothing else. Do lame --longhelp to see what I mean. I don't need every single one of these options, but being able to tweak some settings is of utmost importance to me.

I have yet to find a program capable of this. Hope you can help me. Thanks in advance!

Would grip do what you want? It's a front end for lame, ogg etc and is very good for converting CDs to MP3s etc. I don't know what you mean by tags though, so don't know if it helps in that respect.

I'm guessing there's an apt install for Debian distros.

Why are you named after a through hole diode?

I'd like to have an app like that also. Unfortunately, I believe the kind of thing you're asking for doesn't exist. The *nix software philosophy tends to focus on small, dedicated tools and is fairly against big, integrated packages like this.

Most of the best stuff is cli-only anyway. For audio conversion, sox is probably the best, followed by multimedia encoders such as mencoder and ffmpeg. transcode is a good tool for linking different players and encoders. Tagging can be done with various command-line programs or with gui tools like easytag and audiotagtools, but of course that doesn't help preserve existing tags.

The only good gui tool that I know of is soundconverter. It can convert some audio files and preserve tags between them. But it doesn't satisfy your requirement of tweakability. It can only convert a few formats, and only at basic quality settings.

You might look at the kaudiocreator cdripper also. You can edit the encoder command to add any options you want, and it lets you enter and edit tags. You can also encode wav files from your disk, but only one at a time.

It should be possible to write up a shell script or two using some of the above tools, storing input tags in variables and passing them on to the output encoder. A simple version shouldn't be hard to create, but of course it can quickly become very complicated trying to account for all the possible situations you could encounter.

Good luck to you.