You can use anything that has an aux input, so your connect or amp will both be able to handle this.

so does that mean i can just plug the tape deck straight into the connect and that will then mean i can play over my Sonos speakers?

so i don’t need my amp anymore?

Yes, if that’s the only device, you could certainly plug it directly into the CONNECT. 

So what is the advantage of the new Sonos Amp then? 
 

for me I’m likely to either use the tape deck or very occasionally a turntable… never together so only ever one thing plugged in… sounds to me that the connect will do what I need?

The CONNECT:AMP and its replacement, the Sonos Amp include an amplifier that drives third party speakers. The CONNECT and its replacement the Sonos Port are designed to interface the Sonos system with outside sources, such as tape players, pre-amped turntables, or stereo receivers. They accept line level analog input and send out line level output in addition to the normal Sonos stream. 
 

The PLAY:5 also has an analog input. 

Yes as Airgetlam mentions.

The connect works fine for inputing from a source - - and then its primary function outputting to a device (line level).   Such playing sonos via a receiver and wired speakers in your house.

The Amp (connect:amp) has the same input function … its difference is the outputs are amplified to hook wired speakers direct to it (removing need for a receiver or amp to power speakers).

So for your function yes the Connect (now port), Amp (previously connect:amp), and Play:5 for that matter will all take the tape deck input and do what you want.  All 3 have analog input but then all 3 serve a 2nd different function

Play:5 - built in speaker

Amp - built in amplifier to hook wired speakers

Connect/Port - line level output to another brand amplification device/speakers.

Are you still buying cassettes? Or do you have a collection? I had a decent collection as a kid but upgraded those worth upgrading to CDs. Have any of the tapes worn out over the years? Fascinating. I haven’t thought about cassettes in decades.

I actually just hooked up a friends turntable for him to a Connect.   He has a pretty good sized vinyl collection he wanted to get back into.   Sounded great pumped through his house (he is up to about 10 Sonos speakers now …. got him hooked last year).

I have my CD player wired to a Connect just for getting my CD's into the Sonos environment. In the attic are 500 cassettes and an unused player. Playing these through Sonos would bring back old times!

I’ve been thinking about getting one, Chris. My dad has a huge collection of vinyl, a lot of which I’ve ripped to MP3 a decade ago with a buddy’s turntable, but that is long deceased. I’m looking to get one of my own.

Cool to read the words ‘tape deck’ again.

I’m surprised I’m saying this - but if your dad has a big vinyl collection I would recommend hooking up a turntable to your Sonos.

1.  Listening to a whole album is kind of a lost art
2.  I was surprised how good it sounded.   I know your still converting to digital but it really had a smooth and relaxing sound to listening to an album, especially throughout the house.

It really does. You can’t compare the warmth of vinyl to it’s digital counterpart. Even after ripping it it loses it. What turntable do you have?

I don’t …. I setup my friends …. his was about a 5 year old Sony turntable that happened to have pre-amp built in so it worked perfect.

I’m just surprised you could feel some of the warmth even though it was being digitally converted.   

I haven’t tried it yet through Sonos. I was talking about after I ripped it. Pre-rip the warmth is lovely.