tube choice for Audible Illusions L1


I have a Audible Illusions L1, and it has humming noise on the left channel. I suspect it is the tube. Also, I would like to smooth the sound a bit more. The recommended and current tube I have is 6h23neb. However, I have someone previously recommends Svetlana 6n1p. I would like to try it out, but it says on the AI FAQ that "6NIP tubes should not be substituted as they require additional filament current and their use will compromise performance."
What does compromise performance means? Does it mean the tube life will decrease? But it won't do any damage on the unit, am I correct?

Also, from the tube store, I can't specify the brand. Is it important to order a specific brand?

Besides the 6h23neb and 6n1p, is there other suggestion that will help smooth out the sound, or make it less harsh?

Thanks.
gte357s
thanks for the advice. I will try turn on the cap. It is currently turn off based on recommendation from AI. It won't hurt to try turn it back on. Actually, what is that cap thing?

Also, the Electro-Harmonix-6922 seems worth a try. Not expensive, and it says it may help to remove some of the harshness.

My friend came over and he have a better word to describe other than harsh. It is "dry". It is hard to describe, but when he said this word, I feel it describes the sound.
Gte357s,

The 6DJ8, 6922 and 7308 are a family of tubes that are interchangeable in most audio applications. The E88CC is the European name for the 6922. The 7DJ8 is a little higher voltage version of the 6DJ8. Unfortunately NOS versions of these tubes are expensive and will probably not last very long in your preamp.

This discussion is only going to get more confusing. Get in touch with one of the tube sellers recommended here or in other threads and take his advice. That is the cheapest and easiest way for you to find tubes that will give you the best sound you can get at a price you can afford.
Tomcy6:

The Siemens 7dj8's were still going strong in my friends Mod 3A four years after we put them in the phono section.

Philips (euro) 7dj8's are $50 each @ Upscale and per their ad copy they are fine for use in the AI 3.
Hi Dekay,

How does the Siemens 7dj8 sound in the M3A? Would it help to smooth things out a bit compared to other tubes? I have ordered Electroix-Harmonix 6922. Any experience how they would compared?