48VAC analog waveform
You're asking a broad question, so here are some broad comments in response.

You have a load of approximately 4800 &Omega; and you want to drive about 480 mW into it. Sounds reasonable.

You can easily get low-cost prebuilt modules to do both functions: DDS modules will synthesize your sine wave, and audio amplifier modules can provide the needed power level.

The only detail is that audio power amplifier modules are generally designed for low output impedances (in the range of 4 to 16 &Omega; or so). An easy way do deal with this mismatch is to use a transformer.

A small power transformer with a 24:1 voltage ratio will provide approximately the 600:1 (\$\frac{4800 \Omega}{8 \Omega}\$) impedance ratio you need. For example, if you can find one with a 120V primary and a 5V secondary, you'd be all set &mdash; just hook it up in reverse. A commonly-available 6.3V transformer would probably be close enough; just turn the gain on the amplifier up a bit.

An audio transformer with the required impedance ratio would also work, but would probably be less efficient at 60 Hz.