Question: Disclaimer: I'm computer scientist

I have a sinus wave generator (handyscope H3-5) from TiePie but the output power is insufficient for my application. The specification is [here](https://www.tiepie.com/en/usb-oscilloscope/handyscope-hs3). I need at least 60W. I would like to know if it is OK to connect the generator to the input line of an audio amplifier. I need only a signal below 20kHz.

The amplifier is an SMSL SA 98E. I only have a [french data sheet](https://www.audiophonics.fr/fr/amplificateurs-audio/smsl-sa-160-amplificateur-tda7498e-2x-100w-4-ohm-amplificateur-casque-noir-p-9716.html). The data sheet states that the input line is 400mV-2V.

I'm not sure what it means.

Also I know that the generator is 50Ohms. Do I have to care about that ?

I plan to buy an RCA<->BNC cable. These are sold for video connections. I think they are 70Ohms. Would it be OK ?

Answer: 
> 
> The data sheet states that the input line is 400mV-2V.
> 
> 
> 

That is probably OK; I'd assume you can easily set your output to that amplitude range.

> 
> Also I know that the generator is 50Ohms. Do I have to care about that ?
> 
> 
> 

Not in this case: the input impedance of an audio amplifier will be very high, so that the source doesn't have to drive much load (i.e. be able to supply much curent).

And, at 20 kHz you don't have to care about wave impedances etc: your cable is much, much smaller than the wavelength of a 20 kHz electromagnetic wave.

So, this will work.

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Note that your generator is absolutely overkill.

A sound card would do just as well – these are audio frequencies, after all!

Also, everything but the worst sound cards have astonishingly high fidelity, so that's often an attractive choice. You'll want to be a little careful when using a sound card that it has (or you add) good anti-imaging filtering (i.e. to suppress harmonics that arise from the discrete-time sampling).
All the other answers have adequately covered your question. I'm going to add a reminder that audio amplifiers are not precision equipment.

Your amplifier will be able to faithfully reproduce the signal you give it, as long as you keep your signal within the input limits of the amplifier and as long as you don't "crank up the volume" to the point that the output clips (distorts.)

If the output level is in any way critical to your experiment, then you will need to measure the output level. Your output level is related to the input level by the amplification (gain) of your amplifier, and by the setting of the volume control knob.

The volume control isn't calibrated in any way - you can't rely on it for absolutely reproducible results.

Since you don't (can't) say what the experiment is about, no one can even begin to guess how critical the output power is.

If it's critical, measure it.

As a value for repeating your own steps, the output voltage (peak to peak or RMS) would be a good starting point. You'll need either an oscilloscope or an AC voltmeter to measure it. If you use an AC voltmeter, you'll need one that covers the entire audio range. Common hardware store voltmeters cover just the typical household AC line frequencies (50 or 60 Hz.) AC voltmeters that cover up to 20kHz can be expensive.

For whatever paper you write about your results, you may need to include to actual power into the coil, and maybe the waveform as actually fed into the coil.