Are higher end preamps worth the investment when you are only streaming Tidal & Spotify ?

@puffbojie the ARC preamps you mention are very different from each other. The LS28 is very close tonally and performance-wise to the LS36.5, but the LS36.5 DM version beats it in just about every way. With the right tubes, both preamps can be very harmonically rich while still being quite transparent and resolving. The REF series from ARC are less harmonically rich and more clean sounding, focusing on resolution first. Given where your system is, I believe the LS36.5 or LS28 will be a better fit than the Ref 5.

The Modwright LS-100 is good too, but more colored with more slightly rounded edges than the LS36.5. 

I basically asked the same question about my Eversolo going direct to my Mac amp versus going thru C2300. I got different answers from obviously it would sound better to changing tubes etc. For me, even if going direct sounds better, I would still keep the preamp because it ties in my other components. Digital streaming sounds so good now if one is on a budget, it’s worthwhile considering saving money from buying a preamp and using the savings on better speakers. 

 Very good question…!

I ran my DCS Rossini straight into my ARC 160s and then added my ARC REF 6SE.

Wow….! A massive improvement…! Not subtle. Big noticeable difference in detail, sound stage, openness…. Bass…!

Change to qoboz as someone else said.... A good dac is vital but I spent about 40-50% of total budget on speakers as I always believe end sound most important (river analogy with no point having throttle  at end gotta flow into the sea/ears)

But it's all incremental in the end but big benefits to sound in my books would be speakers/service stream provider/dac/amp/streamer (once past super cheap levels.

Qobuz definitely best SQ streaming service v Amazon HD, Spotify, Pandora, Haven’t tried Tidal.  
 

Looked up the Modwright 150, it’s a beast!  If you can, audition a few high end tube preamps, e.g., Audio Research, McIntosh, then you’ll know and head down the rabbit hole of finding “the best”, mabe an exotic like Manley or a Dennis Had pre, if you can find one or Audio Note out of the UK.