How crucial is the quality of a digital cable?

I remember long ago after experimenting with different analog interconnects thinking that digital could not matter. I swapped digital cables on a CD player / DAC combo thirty years ago ($500 each?) and my jaw dropped. It was as if someone walked in and swapped components several times more expensive. “But it shouldn’t mater!”

Well, you just never know until you try it.

I would look used (used cables.com) and try a 1/2 priced (originally) $100 cable from Cardas, or DHlabs

i would definitely look at a power cable for your integrated amp…these tend to really make a big difference, again, stretch and buy used.

Cables and interconnects can really make a difference. The best thing to do is to try some, maybe above your comfort zone. If you do not hear a big difference… then don’t waste your money. 
 

At some point in your audio journey you will get to the point when they will matter, big time, and you will reap the rewards of your experience.

Yes, a good digital cable matters, IMO. For quite a while I used a Blue Jeans from my CD player to my DAC, as I just couldn’t think it mattered too much, as it was….digital. I finally replaced it with a Silnote, purchased right here through AGone. Yes, more than $100, but it took all the glare out of my digital stream when installed, and much more ‘musical’. The Blue Jeans sounded ‘gritty’ in comparison. Much happier.

If you are going to do it, open up the wallet a a bit and get a good cable. I didn’t spend a fortune on the Silnote, but enough to make a significant difference. Just be aware, a digital cable, or any cable, can be too ‘soft’ or can be too ‘transparent’ depending on your rig, so understand which direction you want to go.

Taking the focus off the cable for a minute- when you use Bluetooth to stream from the amp what are you streaming to?

My experience with digital cables is very limited, so I'll give you my specific situation:

Bluesound Node ($600) connected to Maverick Audio Tube Magic D2 DAC with Sparkos Labs op amps ($400) with a digital cable.

First cable was a Blue Jeans Cable Silver-Plated digital coax ($30).

Second cable was an Audioquest Cinnamon digital coax ($100).

I did not hear any difference with this change in my system.

For reference, I have heard a difference with some power cables in my systems and with changes from Blue Jeans Cable LC-1 interconnects to Audioquest Chicago interconnects to Audioquest Sydney interconnections.

The reason that I purchased the Cinnamon digital cable was a direct result of my positive experience with power cable and then analog interconnect upgrades.

I have a new-to-me Denafrips Ares ii DAC that I am currently the Cinnamon cable to connect to the Bluesound Node.  I have ordered a budget USB cable to see if I hear any difference with a different cable/interface.

I won't say that digital cables cannot make a difference, but the mechanism for a difference being expected is much more challenging to identify.  I'm actually fairly happy that the audiophile rabbit hole seems to have a bottom in at least one area with my system.