upgrade from using linestage from integrated Yamaha

I frequently read others referencing a good line stage as the "brains" of the audio chain. With that in mind, I’m exploring upgrading to a genuine line stage since I’m currently using a Yamaha integrated w/ a Crown XLS Class D amp

Is there an appreciable upside to using a tube stage vs. relying on one from a decent integrated? I know I won’t ultimately know until I try it, but what has been others' experience with a modest $1000 tube line stage replacing an integrated’s ? May I expect a noticeable improvement in dynamics, soundstage properties?
The line stage in the Yamaha is already excellent! I doubt there will be any noticeable difference in sound quality from another solid state line stage. Tubes are another matter! A tube line stage will add its own colorations - hardly what one can call "true to the source"! 
All tube gear - while liked by many - can hardly be called "neutral" or "transparent"! Spoken from experience! I have been collecting and using tube gear since the late '70s. 
i should of mentioned:  my intention w/ a tube stage is to experience how tubes will color things vs. a very neutral Yamaha.  I'm looking at a tubes4hifi SP10.  
There is a Schiit Saga tube line stage available now on eBay. $325 + $25 shipping from Illinois. Seller is "canhthuan". It used a single 6SN7 dual triode. I recommend this one. Why spend more?
That ARC SP10 will be about 3 - 4X more expensive than the Schiit Saga. With just one tube (6SN7) the Saga will be more fun to "tube roll" than the 6922's in the SP10!
There are plenty of good vintage 6SN7's available. Different brands have different "colorations". Plus the circuit of the Saga is pretty simple compared to the SP10! I have an ARC SP6 - bought for its phono stage. 
thanks for the detail - i have a line on an SP10 for less $$  vs. the Schitt, which is certainly a good choice - comes w. a remote vs. nada w. the SP10