Other Rectifier tubes Alternative for 5AR4

The reason I asked is that I have a Musical Paradise DAC which states that I can roll all those different tubes.  I also have a Modwright LS100 and I checked with Dan, he also confirms it is safe to roll these variants.  So, my understanding is that the designer may have one tube that he thinks it sound best, but it is safe and OK to use several other tubes.  The synergy with other components is the key.
I am now using a 5Y3 coke bottle in the LS100 and a 5U4G in the DAC, these gives me the best sound to my taste.  
From my research on the internet, it is safe to roll a 5R4 substitute the 5AR4.  The 5AR4 sound too lean in my system and to my taste.  The other tubes gives more air, I feel.

It’s not an issue in this case since you have directly heated cathodes, but the 5AR4 also has a controlled warmup time to prevent cathode stripping. At any rate there aren't any good subs for it.

Do you mean my amp which is based on the Luxman MQ-300 is directly heated cathodes, so, I need to use 5AR4 where it has a controlled warm up?  And I can’t use a 5R4 because it doesn’t have the controlled warm up?

@wrm57 
thank you very much.