MickB said:
Be aware that some balanced equipment can't tolerate unbalanced connections for long without a dummy load on the 'cold' contact.
However, with your equipment I doubt if that will be an issue.
I think you have managed to conflate the issues of termination and unbalancing.
Unbalancing balanced inputs is easy, you just plug in a plug that ties the minus leg to ground. Unbalancing outputs depends upon the type. Most transformered outputs can be unbalanced by tying the minus leg to ground, as can most servo-balanced electronically balanced outputs. Most ordinary, active-balanced outputs are best unbalanced by floating the minus leg (i.e., leaving it unconnected).
Then there is the issue of termination. Most gear designed and built these days has a high input impedance (10 Kohm or greater) and a low output impedance. The output voltage is transferred, with little effect from the load of the input being driven.
Much of the older gear operates under a standard of power transfer and impedance matched outputs and input loads, often 600 ohms. So some balanced gear, such as the output stages on my 3M M-79 recorder, have transformered outputs designed to drive 600 ohm loads. Each output on my 3M has a built-in dummy load available and switchable, in case it has to drive a high impedance input. If such an output is "unterminated", then its frequency response will usually be affected and will rise in the high end.
This is because the output transformer usually has a resonant peak above the audio band and the design is made such that flattest response and best phase response result when the output is terminated across a 600 ohm load. Removing that load causes a lift of the high end, due to that high frequency resonant peak.
That effect is something that can be exploited: my GR preamp has the same type of transformer balanced output and a front panel switch to load or unload the output, allowing a choice of flat or brighter sound, assuming the output is connected to a high impedance input.
Cheers,
Otto