Audiophile "PA" System??

Here is a new idea:

Health and fitness for me is discipline that goes in and out of favour, but when I do work out, I really enjoy listening to music.

In general, the iPod has been a breakthrough device for this application, but I find headphones a bit fatiguing and claustrophobic.

So I am wondering if I were to set up a small gym at home, what type of system would be reasonably priced, robust enough to withstand a bit of sweat and vibration, and be able to play loudly and sometimes over the din of exercise machines.

Of course, at the same time sounding as sweet and musical as possible and having decent bass response. Can't go jogging to baroque chamber music.

Any thoughts?
By PA, do you mean "personal audio", or "public address" system? If you say "home gym", you probably mean the latter... if so, you can easily outgun a half-dozen exercise machines with some classic Klipsch - going from smallest to largest in size, skipping the obscenely large stuff: Heresy(I/II) / Quartet / Forte(I/II)... also dozens of models of JBLs - lots used in gyms and live venues, several wall/ceiling/post-mount options.

Vibrations? Skip analog, go digital... perhaps even use a wall-mount turntable shelf for your CD-player (carousel?).

At worst (at best?), maybe some pro-audio stuff - like powered monitor speakers (Mackie et. al.), and just a source / pre to drive them?

Thanks -- yes, I meant PA, public address, as in loud with bass.

The pro audio stuff to my ears is sometimes very fatiguing, not what I want when already fatigued from exercise.

Have not heard Klipsch in about 20 years, but I think they are sturdy and probably cheap.

Maybe I should rephrase the question as "college dorm room audiophile" system.

Robust, as inexpensive as possible, used equipment preferred, but still warm, musical, non fatiguing and sufficient bass when shaking the house.

Any and all ideas appreciated.
Klipsch isn't going to give alot of bass, and in wrong systems can be fatiguing. Same with many JBL, so I guess I don't think that's going to be the best bet.

How about this? Wharfedale Valdus or similar low-end hi-fi speakers (poly cones - fast and punchy, lots of very decent bass). I have a pair of Valdus 500s in my basement - great for the money (< $200 for full floorstanders: 2 bass, 1 mid, 1 tweet, dual-ported). The rear port of one of these speakers ripples and waves a tapestry wallhanging from about 2 feet when cranked, and they're designed to take it without breaking up. Very suited to "rave" music - techno, dance etc. as a result - fast, handle tons of power, produce lots of bass. When I'm upstairs with these things cranking, it can sound like the pictures are going to fall off the walls.

Power with a Bryston 3b, some old B&K ST140 (not necessarily bass monsters, but with the Wharfedales, will still produce gobs - this is what I'm using), an old Belles etc. Even a Hafler.

The Wharfedale is definitely robust, as inexpensive as possible, and can be very warm and musical, especially with a warm and musical amp like the B&K ST140. You could do this for < $500 easily. As for robust, the B&Ks are tanks. Stick with the older ST140 though, not any newer B&Ks - the sound changed for the worse in newer stuff.
What about large studio monitors like the EV Sentry 500's. They're large and have tons of punch. Not for a sit-down but will make you get up. Let me know. I know of a pair in storage.
I have a mackie sa1521 powered speaker ($850, 15"+horn) that I recently used as a stereo (using a mackie mixer - you can find these for $150 - as pre) while my 'real' stereo was being worked on and it sounded amazingly good. Way better than their ubiquitous 12" speaker model that all the djs use.
If you are setting up a gym, why not add to the construction and put in a bunch of ceiling speakers? One nice amp/receiver with a 6-12 speaker selector (Niles?) would do great. You could have a built in sub to handle all of the bass. It may save you from blasting to hear what you want. You could just keep a cheapo remote with you to hang on the equipment and adjust things as you go. This would eliminate a lot of problems, ie working out directly in front of one channel and not hearing the other.
I have been using a pair of Bose 402 (Basic) loudspeakers for almost 10 years. They are amazing! Lightweight for portability (1 carrier case holds both at 28lbs total if I remember right). 4 4" speakers in each cabinet rated to 300W. Crystal clear and clean PA speakers

Their newer Extended 402 model has the matching Panaray MB4 Bass Loudspeaker.