I've used convertors on source equiptment and converted, internally to 110V. Shouldn't have bothered, convertor sounded better by small degree but had a bit of mechanical hum.
Trying to find a convertor with the current for amplifiers might be a challenge. Transformers are usually step-down, not step-up. Let's say, for example, that the amp draws 500W. At 220V, thats about 2.25 amps. Double that for the 110V side and double again for "reality factor" and your dealing with 9 amps or 1 KVA. Unfortunately, transformers/convertors are rated for the output side, so you'll probably have to double the rating. Big, expensive convertor.
On the other hand, you can splice into the stove or dryer power and add a split-phase subpanel with dual 15 amp breakers. I've done that and as long as I don't cook an entire Christmas dinner with the stereo blasting, no breakers need to be reset. Difference is that I still use 110V outlets. There are double horizontal outlets and plugs to prevent somebody from plugging a vacuum into the 220V (that would be bad). You have to use wire rated for the source breaker, so you'll need 3 conductor 6 or 8 guage with ground up to the subpanel. Splicing takes ground clips and rubber tape inside a proper enclosure. They don't make wire nuts that big. What you'll have is 2 hots at 110V each (out of phase and complimentary), one unused neutral and a ground as normal. The two hots would be wired as hot/neutral. Might freak an inspector, but it works. Warning: There is some equipment that is not compatible with balanced power.
Trying to find a convertor with the current for amplifiers might be a challenge. Transformers are usually step-down, not step-up. Let's say, for example, that the amp draws 500W. At 220V, thats about 2.25 amps. Double that for the 110V side and double again for "reality factor" and your dealing with 9 amps or 1 KVA. Unfortunately, transformers/convertors are rated for the output side, so you'll probably have to double the rating. Big, expensive convertor.
On the other hand, you can splice into the stove or dryer power and add a split-phase subpanel with dual 15 amp breakers. I've done that and as long as I don't cook an entire Christmas dinner with the stereo blasting, no breakers need to be reset. Difference is that I still use 110V outlets. There are double horizontal outlets and plugs to prevent somebody from plugging a vacuum into the 220V (that would be bad). You have to use wire rated for the source breaker, so you'll need 3 conductor 6 or 8 guage with ground up to the subpanel. Splicing takes ground clips and rubber tape inside a proper enclosure. They don't make wire nuts that big. What you'll have is 2 hots at 110V each (out of phase and complimentary), one unused neutral and a ground as normal. The two hots would be wired as hot/neutral. Might freak an inspector, but it works. Warning: There is some equipment that is not compatible with balanced power.