You may not have control of sloppy recording quality, but if you can recognize it when you hear it, you can avoid wasting money buying expensive wires or equipment to try to improve what can't be fixed.
As for speakers vs. headphones... The same rule of thumb holds true for headphones as for speakers... it's best to spend the bulk of your budget on the transducers, not the electronics. But that said, headphones are never going to give you as good of an experience as really good speakers. Cans are fine for casual listening or times or places when you just can't use speakers. But speakers are the only way to experience music the way it's intended to be heard. If you're really serious about great sound, you need speakers.
Speakers are more realistic IMO as well, but again, this is a headphone site so many people simply dont care about your speaker/ room acoustics advice. However, you CAN get great sound with headphones that is equally satisfying. Listen to a cd player with a high quality discrete output stage that matches the quality of the digital section, connected to a good tube amp and your favorite headphone ....