Arc-PH-5 what tubes should I use

Jafox's response is spot-on. The 6922s from ARC are likely Sovteks. ARC will test them and screen for low noise, so they do offer value. Other tube vendors will do the same, some for half the cost you quoted. Fwiw, you are not limited to 6922s; 6DJ8s and 7308s work fine in the PH5 and PH7.

You can get a quad of Amperex Bugle Boy 6DJ8s for under $100 that will crush any current production tubes.

The best I have tried are 6H23N's these can be had for silly money,about $4 a pop,speak to Anton at gstube.com.

ARC gear has always had an affinity with Amperex tubes especially the 6922 types. These just spank any of the Russian variety’s including the 6H23N's which are only marginally better than your garden variety Sovtek tube.

My favorites are either the pinched waist 6922’s or 7308’s from Holland. A quad of either will set you back a serious chunk of change. Good alternatives which are still miles ahead of stock tubes are either bugle boys or orange globes.