I'm looking to buy an oscilloscope for working on solid state and tube audio projects(guitar and hifi related).  What MHZ minimum rating should I be looking for?  Any recommendations would be greatly appreciated.  Other considerations include single vs. dual trace.  Any brand or model recommendations?

What are your thoughts on these two products?

http://www.sparkfun.com/products/10244
http://www.seeedstudio.com/blog/2010/09/18/dso-quad-is-forming-make-a-wish/

I guess my max price range is around $200 U.S.  I've been looking at some on Ebay.  So many variables.  Some of the old ones seem to have really high starting bids.  Too bad oscilloscope prices aren't dropping like widescreen HDTV's.  I realize the above links are cheap 1 channel scopes with VERY limited MHZ ceilings but what actually does one need to analyze audio circuits for guitar amplifiers and home stereo equipment.

Thanks in advance.

I want to build an LM3886 guitar amp with a couple of tone circuits integrated into the head.  Most likely the tone circuits will be an:

Thor  http://www.runoffgroove.com/thor.html and a
professor tweed  http://www.runoffgroove.com/professor.html

Can I power all three (amp, Thor, professor tweed) with the same bipolar toroidal transformer or will I need a separate power supply to power the tone circuits as opposed to the power amp?

I'd like the power output as close to max for the LM3886 chip driving an 8 ohm speaker but I don't want it "sitting on the edge" of blowing it.  Any specific transformer recommendations would be greatly appreciated.

Thanks in advance.

I just picked up this Micron Dinergy power supply so I could start experimenting.  The secondary connectors are across the top as seen in the picture.  I'll label them as the following :  Ground plus1 plus2 minus1 minus2 (from left to right).

I hooked up the primary wire inputs(towards bottom of picture) to a standard US power cord as follows :  

L    connected to black
N    connected to white
GND  connected to green

I'm getting voltage readings I don't understand:

If I put black probe on ground and red probe on minus1 or minus2 I get -24 volts DC which is what I expected.

If I put black probe on ground and red probe on plus1 or plus2 I get 62 milivolts DC.  I was expecting +24 DC.

Any combination of minus to plus yields a + or - 24 volt reading.  Is the power supply functioning properly?

Any help greatly appreciated.