Circuit Breaker for Dedicated Lines

Look on the inside face of the cover/door of your service panel. There should me a Brand name and "UL Listing". If the Service Panel accepts other brands of circuit breakers there will be a list of brands located somewhere on the label/listing.

Whenever you have additions or repairs to any “Life Safety” system in your home, hire a licensed professional. Call the area “Contractors Board” and confirm that the person doing the work is qualified and match the trade license number to the person doing the work.

Town Building official must approve all work. A $20 fee or so.

Note that if you do not get approval from the town building inspector and your house burns down to faulty / illegal work, your insurance will not reimburse you for damages.

If I had to make a choice, I'd take worse sound over a burned down house.

You can use any breaker that will fit in your slot in your panel for 120VAC (single breaker.) Most panels will require the same make, however, sometimes another make will fit. Breakers are pretty much breakers. Since the wire is protected by the breaker, I would run larger wire than needed(say #10 stranded or even #8 stranded.) Then install a 30 (or 40 if you can find one on #8) amp single pole breaker in the service panel. Stranded wire carries more current than solid core Romex wire. The NEC has been mandating #12 Romex solid wire in the new International Code for receptacles but this is "Special purpose." Use a Hubbell hospital grade receptacle with or without a isolated ground (suppose to help cut noise)
In my dedicated sound room, I killed two birds with one stone. I installed a double 40 amp breaker in the panel and ran one side with a ground and neutral to one outlet and the other side to a second outlet on the other side of the room. You can do this if you have an empty double slot available in the panel or pull your original single breaker out and make a slot. I ran Belden #8 stranded wire with a matching neutral and ground. Don't connect the two together. It would be 230VAC. Connected both to hubbell receptacles and it was the BIGGEST improvment I ever made.
BTW---unless you cut off the complete panel by switching the main disconnect off---the panel stays HOT! If in doubt, call a licensed electrician. Even though you have a 40 amp circuit(2), you are not pulling 40 amps. It just creates a less resistive circuit and will never be a limiting factor.

Ozfly,

The National Electricl Code (NEC) can be found on the National Fire Protection Association (NFPA) website under NFPA 70.

I am a certified electrician and I will tell you that the breakers should be matched at least in compliance with the manufacture recommended type. Its listed on the panel dead front cover. And yes some manufacturers do make compatible breakers for multiple  vendors. 

As far as the best sounding let's get to the basics. First of you should adhere to your local nec code rules which will dictate to the local governing rules and requirements.  

The breakers have to be the right size to effectively protect the circuit conductors and trip in the event it is overloaded and shorted out. 

Do not install a breaker that is larger than the wire can handle otherwise you will potentially burn your house down. I have seen people put 20 and 30 amp breakers on small wires and melt the insulation in their homes. You basically end up having live conductors heating up your 2 x 4 framing and energizing any metallic parts.

The best solution is to install dedicated runs of romex, metal clad or pipe to desired destination. And have quality devices installed including adequate wire or conductors. Make the connections clean and tight and potentially balance the loads at the panel. 

Sometimes the best solution is to upgrade the panel to a higher current type with more breakers. And in some cases you can get away with a sub panel. 

As far as Edison type panels go they are great at surviving and running past the point of safe margins as well as the infamous Zinsco types . These panels have caused many fires in homes and the panels stay on for long times past the allowable levels of safety. 

Be careful and good luck