Preamp upgrade

I have read a bit about don sachs preamps.  It much experience though. 

Pre amps should Always be Tubed....Amps can be either. My Audio-GD HE-1 Xlr has ten tubes...it's the size of a Pizza Box ...and is fantastic for 5K.

Opinion.....Pre amps should Always be Tubed....

Trying to assign a word to whether or how much better it may sound is a mistake.  Will it sound better? Most likely yes.  Will it sound much better in your system with your other present components and warrant a change? Again, probably yes.  Will it crush your current preamp?  Only you can decide.  I’ve listened to the current ARC Reference preamps several times and they’re very good.  I’m not sure how you would be anything but pleased.

To be honest unless you are Elon Musk price matters.

The exponential increase in price of let's say a Ref 6SE over your LS7 will not give an exponential increase of quality reproduction. 

Most of us in this hobby spend a LOT more money than one could justify chasing nuance and the thrill of a high quality new component. 

Therefore; a cost benefit analysis isn't the best way to examine value of Hifi gear. It's more an emotional purchase. In my opinion long after the price is forgotten the thrill of beautifully reproduced music and ultra high quality gear remains.