Does a streamer do anything to the data that Tidal provides?


I have been streaming Tidal to my HiFi for the past 4 years with a streamer and a DAC connected to my amplifier (Raumfeld streamer to Musical Fidelity DAC and also Musical Fidelity Amp). I also have an all-in-one system for my summer house (Naim Muso Qb). So, I know the basics and I am only interested in streaming from Tidal.

What I struggle to understand is, what the streamer does apart from transporting the digital signal and therefore why it could make sense to invest in an expensive streamer.

I understand what Digital to Analogue Conversion does and that it makes sense to ensure a good quality, but isn't the streamer just a transporter of data? Does the streamer do anything to the data that Tidal delivers apart from receiving them and sending them to the DAC? 

Thanks in advance, Michael 
mtraesbo
I was thinking the same way and for years I was happy with a Pioneer N-30 streamer and the nice Metrum Octave dac. Than I decided to give Aries Mini a try. It really made a big difference. In my system soundstage and seperation improved a lot. In fact the improvement was so profound I upgraded again to Sonore microRendu. In my system these upgrades did more than a change of amplifier and a change of dac. I'm convinced now for a good sounding streaming system a good source with quality power supply matters a lot. 
@jaaptina -agree with you totally, and was in the same "streaming is streaming" boat, and was also very surprised on a difference quality streamer makes.
I read a lot of explanation why - and found most of them unsatisfactory, but fact remains. IMHO (and I am not an expert) no matter how everyone claim to be jitter-immune, reclocking, restoring and bla-bla-bla -  somehow corrupted output signal from poorly made steamer simply cannot be restored to a proper quality, with all audible (clearly) issues follow. I cannot however back this up with calculations or empirical data.
@sevs In effect this is a question about which of the two digital volume controls it would be best to use. To be honest I don't know. These days, with DAC's with a 32 bit internal bit depth, digital volume control should not be an issue. Intuitively, I wouold concur with the idea to keep the volume on the Ipad at (near) max, and also on the Chromecast (it also has a software volume control). But this presumes that the Wadia has enough bit depth to do the job (75% is a troublingly modest claim). I wonder if Shadorne can inform this discussion.
@willemj thank you! For now I will keep volume at 100%, to be on the safe side. Strange that Chrome has no mention of this, and when asked at Chromecast chatroom they dismiss or ignore the question.
Sorry, I misquoted Wadia, the manual actually says 65%: "If you find that your typical volume level during critical listening is below 65 on the volume display, it will be advantageous to use a different [internal gain] setting" Since I keep volume at 100% and use NAC52 volume knob, I was not paying much attention to the exact number.
Wadia manual says that their "Glass optical, as implemented by Wadia" input gives the best results (then AES/EBU--Coax_BNC--coax_RCA--TOSLINK plastic-optical) Right now I am using $6.99 plastic mini-Toslink, should receive WireWorld glass mini-Toslink tomorrow.