Tube Flavor

OMG...  Don't do any tweaks at this time.  There is no need to have the same brand tubes in your amp and preamp.  It is best to look and see what others have tried.  NOS tubes are a good option, but my concern is once you find the sound you like can you get the same tubes later?  Call the folks at tubedepot and vivatubes or other reputable dealers to get some options.  Personally, I like Telefunken, Mullard.   But every system is diffrent.    As far as cables i would suggest Cardas because of the quality of copper and structure.  Avoid gimmick brands that have quantum tunneling,  magnets, etc.  

I have a tube preamp and tube mono blocks. Here is my experience.

First, I looked up the stock tubes that came with my gear. All JJ tubes. Not expensive. Decent. I consulted some folks on Audiogon and they suggested the preamp could be bettered, first. I contacted Brent Jessee and told him what kind of sound I was looking for. He suggested a very good signal tube. I went from tubes that were about $12.50 each to tubes that were $50 each, both NOS. They sounded a lot better. I listened with those for a while, getting used to their sound. (I do not have the ability to do "left-right" so I just changed them. They burned in a bit and sounded mellower and better after about 40 hours.)

After I had gotten used to the NOS tubes in the preamp, I asked Brent again about the mono blocks. He set me up with new input and driver tubes, all NOS. About $300 or so for 4 tubes. I put them in and lived with them for a while. They improved the sound quite a bit.

Finally, at a certain point, I was still hearing some harshness I wanted to try to tame. I swapped out the KT88 tubes for KT77 tubes and heard quite a nice change. Now I go back and forth on those output tubes and enjoy the variety.

I don't know what Raven puts in there, so consulting with the maker is good advice. Most manufacturers want to put in decent tubes that are available in good supply for customers. They don't want to break the bank on tubes in their stock units because they add to the bottom line for the customer and make their amp prices less competitive for no solid reason.

In contrast to the advice above, I cannot do left/right comparing because I have no balance knob.
I don't find tube rolling to be a waste of time; it's a simple change that yields interesting differences.
I don't find NOS tubes to be extraordinarily expensive. Yes, there are some outrageously priced tubes, but that is not all there is out there.
I have found NOS tubes, if tested by a reliable seller, to be reliable.
In addition to Brent Jessee, I have had very good service from Jim McShane.

@oldhvymec I recently had my ears tested and one ear is better than the other. Are both your ears equally good? If not, do you know how to compensate for that when you do your left/right testing? Regards,

Few years back i would stand that NOS tubes or tube rolling could bring nirvana. After spending so much money and time i came to the point that it is not that big deal after all. Still though some of them do worth to try but proceed with caution.There are better ways to spend in your system.
Good thing i made a profit selling all those nos tubes and learned so much about them.

+1 The approach used by Hide45.