Sorry but for these audio-related frequencies, especially when probing around in vintage equipment, all the termination issues are BS... Inside the equipment, you will be using 10x or even 1x probes at the input(s) of your 'scope. Actually, working in audio gear is one of the very few areas where it may make sense to use switchable 10x / 1x probes and configure them to 1x.
I think the termination issue was introduced since you want to measure the internal waveform generator of your scope. These generators have an output impedance of 50 ohms. Usually, you can set up the generator if it the load it's attached to is 50 ohms or high-impedance. Some generators even offer to enter arbitrary values. This doesn't change anything on the generator output, it's still 50 ohms, but it's used to calculate the signal level accordingly. As an example, if you adjust your AWG to output 1Vpp into a high impedance load (i.e. a "classic" oscilloascope probe), you will measure (more or less) exactly this level. If you configure the AWG to 50 ohm load impedance and adjust the level again to 1Vpp und still measure with the high-impedance probe, you will just measure twice the voltage (2Vpp). The AWG takes care of the voltage divider consisting of the impedance of the AWG's output stage and the load resistance the signal is (told to be) fed into.
Proper termination of transmission lines (coax wires...) of the "usual" lengths becomes relevant if you are working on RF gear (say > 1MHz), or basically, if the length of the wire get longer than about 1/20th of the wavelength (on the line) of the signal. Just use your scope's probes for audio and lower RF stuff and you should be fine. Get used to it and after some time, you will know what probing technique may be required for a certain signal.
What's very convenient are those BNC-alligator or clip leads for injecting signals (be careful not to touch any contacts that carry a signal and may feed it back into the AWG - this could be fatal (for tha latter that is) and always make sure the grounds the probing and sourcing leads are connected to are identical. If you can't eliminate a ground potential difference, use an audio signal isolating transformer at the AWG/s output. This will eliminate the ground loop through the oscilloscope. Alternatively, a (higher voltage) active differential probe is a very recommendable thing, look out for the MicSig ones since they are quite affordable. Yet they most useful for high(er) signal level measurements.
A 50 Ohms feed-through terminator may be good to have anyway if you eventually intend to attach some other active probes that may be calibrated to feed into such a load. But it's not required right from the start.
Just my 2 cents...
Cheers,
Thomas