Victor's 1kHz oscillator (which is way better than these plots) into PCM4222EVM single-ended plus noise floor for reference:
Don't let the lowish noisefloor fool you, a large-windowed FFT plus a tad of averaging does the trick. Yet, the harmonics and main signal doesn't change their amplitude thus the large windowed FFT does the trick on lowering the noisefloor only.
By the way, these Victor's oscillators are GREAT, and their performance has been confirmed on DiyAudio by low-distortion maniacs :)
Can be purchased over epay, http://www.ebay.co.uk/sch/mickevich/m.html
E-MU 0404 PCI DAC to PCM4222EVM ADC:
E-MU 0404 PCI DAC to E-MU 0404 PCI ADC:
Some noise floor measurements.