Reel to reel

2-track 1/2" tape at 15 inches is amazing. But be forewarned- you won't want to listen to 1/4" tape after that...
1/2" 2-channel is a common mastering format.  

Atmasphere is quite right. I only have a handful of 1./2 inch 2 track 30 IPS masters -stunning. But a 1/4 inch 2 track 15 IPS tape with Dolby SR comes pretty close.

I can see the dilemma, Inna.  This one tape's cost of admission is $200, on sale with free shipping for the sale.  I am quite aware that this tape may make it difficult to go back to LP's, but alas, saving for retirement limits that kind of discretionary income purchases to no more than a few a year.  

The good news is my Yamaha A-S2100 finally arrived and it will inserted into my system and thoroughly tested and "burned in" (I doubt there is such a thing with SS amps, but what do I know?) by the time the 15ips 1/2 track tape gets here... I'm on pins and needles.. :)  A review will be forthcoming soon.  

My new to me Revox B77 high speed arrived today.
Played a couple of pre recorded 7.5ips tapes through it and very impressed.

Next up is trying recording at 15ips from Qobuz hires stream.

As you say it may then be hard to go back to a lower level.

the first hit is free.......
but IF you are contemplating 15 IPS then $800 for a tube head preamp is trivial....

@tomic601 .

Interesting perspective......
If I win the lottery $800 may become trivial but until then I think 15ips will remain an experiment.