Newbie Tube Questions

Hi there,

I'm absolutely new to tubes and I really don't know anything so I need a little help from you guys.
I bought a brand new Consonance M99 Plus integrated tube amp for 380.00 (1/3 of the retail price in the US), in Shanghai last week and have a couple of questions (have copied the description below):

1)External individual bias adjustment for each 6P3P...whats this and how to do it/benefits ?

2)The guy in the store, with VERY elementary english told me that I could change the 6P3P tubes with either EL34 or KT66....what are the sonic characteristics of these tubes ?

3)Is it worth to put higher quality tubes in all three stages ?

P.S.: The amp is hooked up with a Shanling CD-S100 CDP that I bought for 150.00......and please don't ask me how I got all this inside my luggage.

Thanks !!!

+++

Consonance M99plus tube integrated amplifier

The fifth anniversary model, with volume and input selector. Due to reasonable input sensitivity, can be connected direct to CD source. If connected using the T99 pre-amplifier the sonic result will be even better. The circuit composes of there stages: Sovtek 12AX7LPS (ECC83) as the first SRPP stage, followed by Shuguang 6N8P (6SN7) driver stage with Shuguang 6P3P (6L6GC/KT66/5881) as the final power stage in class push pull class AB configuration. This is a classical circuit and the sonic performance is very high due to the design of the output transformer, tube circuit optimization and years of experience in the development of the M100SE. Uses fixed bias design with external individual bias adjustment for each 6P3P.

Control Functions: Volume, Select, Power On/Off
Inputs: CD, Aux and Line in

Specifications:

OUTPUT IMPEDANCE: 4,8 ohms. (User selectable). )
Output Power at 1 kHz for less than 1%THD: 25W x2
Bandwidth at - 3dB: 6Hz to 60kHz
Input Sensitivity for Rated Output: 180mV
Signal / noise: 90dB
Input interfaces: 3 groups (RCA)
Input Impedance: 50k
Consumption: 90W
Tubes: 6P3Px4, 6SN7x2, 12AX7x2
Dimension: 446 (L) x 264 (W) x 155(H) mm
Weight: 17kg(Net); 21kg(Shipping)

+++