Re-wired to 30 amps?

No one has even mentioned line surge impedance. The lower the better, let me repeat that: The lower the better.
Theories aside - always use at least 10awg wiring - your ears will thank you.
Any faults drawing significant current will hardly draw the line at just below the fused value. If you're worrying about that then you really need something to do.

For Speakerdude:you right-if you will go from 10AWG to 8 or even 6-will be significant improvement-I already experimented with my dedicated line (I am electrician):just what you need do right-install 20 amp circuit breaker,because your receptacle 20amp(or 15amp,it's same).

Glad to see that others share my experiences. If some of you folks remember back to when we first started discussing dedicated lines on this forum, i was recommending 8 gauge for 20 amp circuits. I still think "heavier is better" but most folks think that 8 gauge is WAY overkill. It may be IF you have a very short run from the breaker box to the outlet. As such, i've "toned things down a bit" and figured that if i can get them to at least go up one step in commercial wiring ( from 12 gauge to 10 ), it would still be a step forward. When it comes to ANY type of power supply ( AC lines ARE "power supplies" ), bigger and lower series resistance is ALWAYS better. Sean
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One problem with 8 gauge or lower is the difficulty in working with it. I'm a few weeks from moving into a house with dedicated 10 gauge lines. I have easy access to the same type of wire and am thinking about experimenting.

I could wrap and solder another 10 gauge line (hot to hot, neutral to neutral, ground to ground) just in front of the connections on both ends. There would then be two solid core lines running side by side. That would leave a 7 gauge run for most of the length and 10 gauge right at the connection points (well, maybe a couple of feet on either end depending on access capability). The total run is about 25 feet from the breaker box. Is this a crazy notion? At the end, it's always "let your ears decide", but this would be a bit of work and I'd rather avoid it if it won't make any difference. Thanks.

anything larger than #10 is very hard to work with especially solid conductor; another reason to stop there is that #8 or larger does not typically fit either the fusebox or outlet connections.
Oz - splicing smaller conductors onto the ends of a larger gauge run is probably not a good idea. You'll have two extra/un-necessary degrading connections, thus offsetting the benefits of the larger run in between.