One of the advantages of having a full-blown home stereo receiver is that it's more versatile than a compact all-in-one audio system. You can add components as needed or connect a microphone and use it for karaoke or as an impromptu PA system. It's easiest if your receiver has microphone inputs, but you can work around it if not.
When You Have an Input
A lot of stereo receivers make life simple for you by providing a microphone input on the receiver itself. Depending on your receiver, it might have an old-school quarter-inch jack or the smaller 3.5 mm type, but both work the same way: Plug in the microphone, turn it on and start talking or singing. What happens after that depends on how sophisticated your receiver is. Older or less sophisticated models don't have any way of adjusting the microphone separately from the main volume, which doesn't work well for karaoke. Higher end models such as the TSR-5830, a Yamaha receiver with microphone input, detects when the 3.5 mm jack has a microphone plugged in and corrects the volume to match your stereo sources.
Home Karaoke Mode
Some stereos are built specifically to accommodate karaoke, which is even better. They often provide more than one mic input so you can harmonize – or fail to harmonize, which can be even more amusing – with a friend. These units usually have a separate level control for the mic so that you can be heard over your music and a loud singer won't drown out a quiet singer.
If your receiver is a new model or if you're buying one specifically to work with microphones, you might want to consider Bluetooth technology. New receivers often have Bluetooth, which allows you to stream music wirelessly from your portable devices, and it works just as well with a wireless microphone or headset. The only potential downside is that Bluetooth mics are usually meant for voice calls, rather than for singing, so if you want one for vocals, you need to look closely at the mic's dynamic range before you make a purchase.
Using a Mixer or Audio Interface
If your stereo has no home karaoke features, Bluetooth or microphone inputs, you need a separate piece of equipment to help you connect a microphone. A small mixer or audio interface connects two or more microphones and then attaches to your stereo receiver through either RCA cables or a digital audio connection, like any other piece of equipment. It's an added step and an added cost, but the upside is that you have a lot more control over the mic volumes. Depending on the unit you buy, you may also be able to attach more microphones – for group singalongs or panel discussions – or even mic a musical instrument or two and play along with your favorite tunes as you sing.
Microphones for Your Home Stereo
If you already have a mic, that part's settled. If you're still picking out a microphone for your stereo receiver, you have lots of options. A traditional dynamic mic, which requires no power, is a good choice. They're relatively inexpensive and physically durable, which is why bands use them by the dozen. You might also want to look at condenser mics, which require a battery but are more sensitive. They're great if your singing style leans more to a gentle croon than a full-bore bellow. You'll also have to decide on the mic's pickup pattern, which describes where the sound comes from. There are lots of options, but in the living room, your best bet might be a cardioid mic. Those pick up sound only in the direction they're pointed, which means you're less likely to get feedback from your speakers.