Buffer or true bypass? The question is as old as some of my socks. If you hang out on forums or google the topic, you will find endless debates about buffers vs. true-bypass. The good news is that it is not a binary decision. Here's what I've found over countless tone experiments moderated by liberal amounts of beer:
So what is the quickest way to gauge the efficacy of buffers in your setup? Easy. Stick any modern Boss pedal at the beginning of your chain, and another at the end. The Boss (or any good buffered pedal: Maxon, Ibanez) etc. have the buffers always on. You should be able to tell pretty quickly what's what.
On caveat: some older design pedals are famous for their distate for buffers. The classic example is the Fuzz Face--it simply doesn't sound the same if you have a buffered pedal in front of it.
So what about building a buffer? Glad you asked! Buffers are some of the simplest DIY projects out there, so lets dive in a look at some examples.
Here is a very simple and effective buffer from Jack Orman.
Using a low-gain JFET transistor, this design is as simple as it gets--input cap, bias resistor, and output cap.
Next up is the single-transistor buffer as found in the Ibanez Tube Screamer--a bit more complex, but your ears will be the guide as to whether or not it sounds better.
Opamps make great buffers. Here is another design from Jack Orman that uses a TL071 part. The 9 volts shown will work, but if you bump it up to 12-15vDC you will get more headroom for hotter signals.
Here is the opamp-based buffer section from a famous boutique overdrive that rhymes with "Plon Fentar". The Plon Fentar has a buffer that is loved by a lot of people, including those who profess not to like buffers! This has a few more parts. Again, let your ear be the ultimate authority.
You can build a simple buffer using any kind of stripboard/perfboard. Closer to home for my U.S. visitors is the local Radio Shack. Get one of their IC boards, part #276-159B and follow the wiring diagram below. In fact, you should be able to get every part for the simple project at Radio Shack if you are so inclined.