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
I am very confused. So, the Amperex 6922 is not good? From the AI FAQ, it says:

"Only "mil-spec, low-noise" 6922, 6DJ8, 7308 or European E88CC tubes are recommended for use in Modulus preamplifiers.

Previous production Modulus M2, M3, M3a and L1 preamplifiers used Russian 6922 tubes. While quality and sonic performance of these tubes were excellent for several years it is unfortunate that current-production from the Sovtec/Reflector factory does not have the same sonic identity and a high percentage prematurely fail.

Current production Modulus M3a and L2 Preamplifiers use a Russian Military Type 6922 with "Grey Plates" and have excellent sonics and reliability.

Similar tubes which have different technical specs should not be used.

7DJ8 tubes require higher filament voltage and performance is marginal.

6NIP tubes should not be substituted as they require additional filament current and their use will compromise performance."

So, the 7D8J and 6N1P conflict with Joe's comment. And Joe said 6922 is not suitable? ... So, the remaining choice are:

6h23n, 6DJ8, 7308, E288CC ?
Previous production Modulus M2, M3, M3a and L1 preamplifiers used Russian 6922 tubes.
09-24-10: Gte357s

Gte357s,

You have the L1 correct?
>>>>>>>>>>>>>>

09-24-10: Audioconnection
Go inside the unit and make sure the Cap dip switches are set to on
the amp you are using may better interface this way.
Also call AI with your serial number and they will
get you the right tubes for that unit
Best Johnnyr
Sounds like good advice.
>>>>>>>>>>>>>

09-24-10: Theduke
Get some choice EH6922. Try "The Tubeman". He has cyro'd tightly matched triode pairs available.
Also good advice
A good rugged tube.
http://www.upscaleaudio.com/6DJ869227308_c_42.html
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.