Signal generator for ADC testing

[s55]

I need to test an 1GSPS ADC to measure the SNR, by applying 3~400MHz sine input signal. At least two signal sources are required to do this: one for sine input signal, and the other for clock source of an ADC. As a researcher, I'm trying to purchase the signal generators, using my research funding.

Basically, I need 2 external signals for testing. Here is my question.
I can buy two signal generators, each of which has a single output channel. Or I can purchase one generator which has two output channels. Which one is better?

 

[FvM]

The ADC clock source will be usually designed into the signal processing board, I don't see a purpose of using an external generator. For the sine signal, you'll refer to a standard RF generator.

 

[s55]

FvM, thanks for quick answer.
Unfortunately, I don't assume a clock source on the board that is usually a crystal, since my ADC samples at 1GSPS, and crystals support way too low frequency compared with 1GHz. Actually, the following link shows my target setup:
https://wiki.analog.com/resources/eval/hsc-adc-evald

 

[FvM]

I thought first of available digital clock synthesizers that could be integrated with the board, but I realize that you may want a low phase noise clock source to fully utilize the ADC performance. So a high quality lab generator might be preferable. Still think that separate instruments are more flexible.