PrimaLuna preamps. Use of 5R4GY tubes instead of 5AR4 / GZ34. Yes or no?

yukio:
I have used them (Philips 5R4GYS) for several years now. Improvements are a little more warmth on the top end and a small increase in sound stage width.
I failed to mention the Philips tube is substantially taller than the stock 5AR4 tube and when in position you will no longer be able to use the tube cage.
Please note again that as a general rule, it's not a good idea to deviate from a 5AR4 tube and it remains a good idea to consult with Upscale Audio.

He's saying 5R4GYS not 5R4GY.....

Read this in case you're interested in more detail:
https://www.diyaudio.com/forums/tubes-valves/67523-5r4-gy-5ar4.html

yukio,

Simply either go by what is on the website or call Kevin Deal at Upscale Audio, he is directly involved in PrimaLuna beyond selling them

@Kalali..5R4GYS and 5R4GY is the same tube. The values are the same