What is your best kept secret in mid-fi?

Dedicated Circuits. Worth every penny in improved sonics and actually would have saved me time, money, and hassle if I would have had them installed sooner rather than later.

Invest in discs and LPs that are made using the very best recording and mixdown techniques and equipment. Although such media usually is more expensive than the average product, the resulting audio quality, even when played through a "MidFi" system, far exceeds the subtle improvements possible (?) when the typical disc/LP is played through multimegabuck equipment.

Give up the lowest frequencies (<40-50Hz), which allows you to use smaller speakers which in turn can be easier to drive. You'll get better performance above 40-50Hz for a reasonable cost, and your amplification will be cheaper as well.

Newer is not necessary better. There is nothing wrong w/older technology. Especially true w/tuners. Good sound can be had for very little $. Recently been shopping on "E-bay" and have bought excellent older equipment for cents on the dollar. Most of the equipment I remember reading about or actually using/or selling. Always check on the seller's feedback and e-mail them a question.(Make sure they know how to pack well!) Interconnects/spk. wires/power cords are very important. Don't skimp and buy used if possible. (Not always the cheapest! I've seen Van de Hul's selling for more
than ordering new directly from England.) AC conditiong is very important as well as having dedicated lines if possible. At the very least change the inexpensive outlet to a higher-grade outlet. Clean your contacts. Seperate your interconnects/spk. wire from AC cords. Equipment break-in/settling time is very important. Do your research. Reading these forum topics you'll get a sense of the equipment's orientation, whether on the lean or warm side of the spectrum. It all boils down to system matching/the room and a person's expectations. Hopefully you'll put a satisfying system together on the first time around but this unlikely, that's why it's very important to have lots of pieces around for the puzzle! :) Once you get "it" right, sell off the excess and get off the "merry-go-round" and be content if possible.

I agree with Rsbeck, however I’ll take it one step farther and say put one or two 5 KVA (or larger) isolation transformers into the equation. If you thought the dedicated circuits were a great improvement, wait until you hear the additional improvement using the isolation transformer with or without the dedicated circuits. Of course the dedicated circuits with cryo’d outlets and the isolation transformer is the way to go.
It’s hard to believe how good a mediocre or good sound system can sound with clean filtered power!