Which gives better results inexpensive DAC or inexpensive tube Bluetooth pre?

I am an old school newbie when it comes to DACs and Bluetooth and still listen to vinyl cassettes and preferred tubes over solid state.  
I listen to Spotify thru an old phone or iPad plugged into my preamp via an RCA to mini plug, in addition to CDs, cassettes, vinyl and a tuner for sources so I am not into streaming yet.

i have friends who stream from their computer and are all about having a good DAC, but yesterday I met someone who had several amazing sounding systems and he had an $80 tube Bluetooth preamp in order to listen to his iPad wirelessly.  The several systems I heard yesterday are well above the lower end high end gear that I’ve had and just curious which is better - spending money on a separate DAC or a cheap Bluetooth preamp?  I like the idea of playing my Spotify wirelessly.  
I’m not ready for Roon, Tidal, a streamer or getting into it more as I have lots of music that I enjoy.  I’d just like to get better fidelity from Spotify and be able to listen to it wirelessly.  TIA :)

If you want to stream wirelessly, try the Auris BlueMe HD. It's a top notch $119 bluetooth receiver that also has a decent built-in DAC. I use the predecessor (non-HD) in my system, and it is very good. You can use it's analog outputs into your pre-amp, or you can buy a higher-end external DAC and use the digital out of the Auris BlueMe HD and connect to the upgraded DAC.

I use the Auris BlueMe to improve the SQ from Spotify, Radio Paradise and YouTube. Radio Paradise can sound very good as it supports bitrates up to flac.

I'm listening to Radio Paradise in flac, and streaming from my laptop via bluetooth to the Auris BlueMe, as I'm typing this....... 

Great stuff.....
Try the Topping DX3 Pro.  Has built in BT, as well as functions as a straight up DAC.
Thanks Rueben, is listening to my Spotify without a wire considered “streaming wirelessly?”  Because that’s all I really want to do at this time with better fidelity / the best fidelity available on a shoestring budget.  

@lou_setriodes  - Listening to Spotify, wired or wirelessly, is considered Streaming. Spotify, like Qubuz or Tidal, is a streaming music service. You're streaming the music, regardless of a cord, or not.

I've not heard the Topping unit that Eric recommended. However, if it has a quality bluetooth receiver built-in, it might be a good choice. The Auris BlueMe HD is a really good bluetooth receiver and it's built-in DAC is adequate. Most of the time, I liste to mine connected through my external DAC, but it sounds good via analog output (built-in DAC) too....
Just a thought. I realize that you’re budget minded, but you might want to consider another service other than Spotify. Tidal, Qobuz, even Amazon HD, will give you better quality files than Spotify.