Tube Preamp: How many tubes does it take to .................

Just because a preamp has multiple tubes doesn't necessarily mean they all have to be matched. I know of a line stage that has 10 tubes in the signal path and only pairs need to be matched.

@elliottbnewcombjr 

Your  McIntosh Tube preamp in picture must be a maintenance nightmare.

I had same bad experience with a AR sp-11 phono/line pre-amp 20 years ago. I bought the unit based on great audiophile commentator Mr. Chen's recommendation.  I was impressed with the phono stage performance. Howerver, very soon, I ran into multiple tube bias issues and component(s) failures. I felt a pre-amp should not require to be baby sitting every 6 months to keep running at optimal state, so I gave it up.

My current  hand made line stage preamp are all single tube stage amplifier based on famous Western-Electric "Ultra path" circuit using best nickel signal transformers and Teflon coupling capacitors, and it out perform AR SP-11 by a big margin.

Furthermore, tube type matters in line pre-amp.  26 direct heated triode sounds best in a cost no limit pre-amp design.

In relation to matching tubes, it certainly is a Horses for Courses subject.

Unfortunately the right horse is not found until tried in the race, pretty much the same for a Tube Roll experience. 

I have had a supply of Brand New Tubes, that when tested, the equipment owner made known immediately one Tube will produce sound, but is with a fault. It was an unknown how such a fault could impact on a circuit, which resulted in the suggestion not to use the tube.

How many individuals are putting New Tubes into their equipment not knowing how it measures on receipt to them, and prior to be put into service.

I have had tube equipment for more than two decades, I have developed my own disciplines, maybe a little cautious, but through careful practices, there is a plan for the usage, that has prevented the worst type of the associated stories occurring so far.   

I think that sound reproduction fidelity is inversely proportional to the number of gain devices.  So do a lot of people.  Accordingly, I don't think it's coincidence that the best sounding preamp that I've ever heard uses only one-half of a double triode tube per channel as the entirety of the gain structure.  It's the Dodd Battery Powered Preamp.  A simply extraordinary amplification device.  No voltage rectification.  Huge signal to noise ratio.  Remarkably linear and remarkably transparent.  There's a reason Danny Ritchie still uses one to demonstrate his speakers.  To paraphrase Danny: "If I knew of something better I'd use it, but I don't."

My ARC SP9 MKll has one tube for the line stage part and one tube for the Phono section.