How to match ohms with amps & preamps

Thanks. At least that gives me something to go on. Does the same apply for digital sources plugged in directly to an amplifier?

It depends on how the digital source outputs to the amp, if it has a traditional analog volume control with op-amps or some other kind of buffering it should be the same if not better considering the fact you will have one less interconnect in the system (unless you end up using longer a interconnect). If you were using a passive pre-amp things get more complicated, as the impedance will change with the volume control setting . Cables will always be a consideration when connecting components, more so when going passive. The new all digital (Tact, etc.) systems should present less of these problems.

Historically, the accepted ratio was that the input impedance of the device receiving the signal should be a minimum of ten times the output impedance of the device sending the signal and the greater the difference the better.But, as with every rule there are exceptions, certain Krell and Rowland models are optimized for currnt transfer and signal transmission is optimized when the two impedances are matched.