A transformer is best when it doesn't approach it's limits. For that reason, I suggest using at least double the draw. So I agree that 500 VA to 1 KVA would be better.
Also, a transformer can have a mechanical hum, espescially when overworked or supplied dirty power. The benefits of a transformer are elimination of DC offset and roughly 12 dB noise reduction (toroids being half that but less likely to hum and more compact). Good for ground loops too. There is some draw at idle but they are efficient enough to not worry about leaving powered.
Signal Transformers has a DU series that is shielded, Q-rated and steps down to 104V. These are not in boxes and do not include plugs.
I have never experienced any drawback using power transformers aside from one (of several) humming but that one was scavenged from industrial equipment. I have used them for isolation and to convert to balanced AC and in all cases, the sound was improved. Sometimes subtle, sometimes amazing.
Also, a transformer can have a mechanical hum, espescially when overworked or supplied dirty power. The benefits of a transformer are elimination of DC offset and roughly 12 dB noise reduction (toroids being half that but less likely to hum and more compact). Good for ground loops too. There is some draw at idle but they are efficient enough to not worry about leaving powered.
Signal Transformers has a DU series that is shielded, Q-rated and steps down to 104V. These are not in boxes and do not include plugs.
I have never experienced any drawback using power transformers aside from one (of several) humming but that one was scavenged from industrial equipment. I have used them for isolation and to convert to balanced AC and in all cases, the sound was improved. Sometimes subtle, sometimes amazing.

