Which Amplifier to get

What are you powering with the amplifier, speakers or just headphones? If speakers, the power amplifier must have the ability to supply the necessary wattage to the speakers. Don't just purchase an amplifier with an arbitrary output wattage. Good rule of thumb if you're using larger speaker is the amplifier should supply 1.5 times the wattage of the speakers. i.e. 100 watt speakers should be driven by a 150 watt amplifier.

If only headphones, consider a headphone amp with quality opamps. You can find loads of info about descent headphone amps on audiophile websites or forums.

An amp must never under power the speaker. A 1000 watt amp can power a 10 watt speaker at low power just fine. But an 80 watt amp driving 300 watt speakers..This is far worse than supplying to much wattage. You will literally destroy the speakers by melting the voice coil.

You will need something to switch between audio sources of the cable box and the phono pre or what ever else you own. Unless you want to manually disconnect and reconnect the source audio cable each time you desire to switch between the two sources.