DAC DIRECT IN TO AMPLIFIER OR TO PREAMPLIFIER
For the longest time, I believed that the best preamplifier is no preamplifier. Eliminating a component from the audio chain would yield less distortion & greater purity.
Recently, I have had reason to re-think my logic on the matter - and I am (I think) changing my mind. Better said, assuming that the preamplifier in the component you are using (in my case, a DAC) can produce 95% or greater quality sound compared to the preamplifier component, then no preamplifier is the best option. The 5% represents the (estimated) loss of fidelity in adding another set of interconnects.
That said, most DACs do not have an outstanding preamplifier built in. I think most have average passive attenuators, and the better DACs have active preamplifiers that are very good - but not as good as a quality preamplifier.
What are your thoughts?
My experience goes back so many years it might not be useful in discussing modern equipment. Many years ago I ran an old Phillips CD with variable output directly into my amp. I thought it sounded pretty good. Then purchased a Conrad Johnson PV9a preamp and added it to the system. It was a noticeable improvement to me. Separately, I found this Bascomb King interview on the subject interesting. |
The case of output impedance rising in the lower frequencies was not unusual amongst tubed preamplifiers. I believe it was related to the size of the coupling caps used. With almost any tubed amplifier, and with most SS amplifiers, the rising output impedance wasn't a problem but there are some SS amps like my SMc modified monoblocks that have input impedance of only 10K ohms, or some of the earlier Pass Labs amps that had input impedances of 20K or 22K ohms, where a high'ish output impedance from a tubed preamplifier might roll off the bass early. The rule of thumb was to have an input impedance of at least 10x the output impedance, but I have always preferred to see at least 20x. |
I concur. After conducting some research, we could apply the general guideline of a 3dB cut-off frequency at 2Hz to calculate the desired load input impedance (RL) in ohms using the formula RL = 0.5 / (π * f * C), where f is the cut-off frequency (2Hz in this case) and C is the capacitance in Farads. For a better understanding of why 2Hz is suggested, you can refer to [https://www.v-cap.com/coupling-capacitor-calculator.php]. The Aesthetix Calypso Standard (Saturn) series employs 2uF output coupling capacitors. Therefore, the desired RL is calculated as RL = 0.5 / (3.1416 * 2 * (2x10^-6)) = 40k ohms. This calculation aligns with JA’s measurements in the lab. Now, if the load input impedance at the amplifier doesn’t match the desired 40k ohms, one possible solution is to replace or upgrade the 2uF caps with the 4uF Dynamicaps used in the Signature series. This would reduce the desired RL to 20k ohms, resulting in benefits such as improved bass extension, resolution, dynamics, and reduced grain. According to the manufacturer’s website, the existing Saturn units can be factory upgraded to Signature specification. Alternatively, you could consider purchasing the Signature edition. In the used market, the Signature edition typically costs around $3,800, compared to the sub $2,500 price tag for the standard version. |
Dealer OCD Mike peddles a 22k Playback Designs DAC that voids all preamps apparently on most of his videos. This video is no surprise. It is very doubtful that the dude's dac does endless miracles with every amp on earth.. It is not that much a mystery that amp manufacturers will design a pristine sounding poweramp and pretty much try to lock you into a pristine sounding $$$$ preamp they specifically designed for it (atleast in the high end). All the DACs and the preamps from other manufacturers can sound less optimal thereafter with that poweramp (Not always though and there are enough exceptions, of course)..
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I am going to get the Dream DAC (not from OCD Guy). This is my last item to get. I will not use the DAC direct to amp. I will use it with the $2500 Benchmark LA4 preamp. I can actually test the quality of the Dream direct to amp if it has RCA outputs. My CODA #16 amp has a nice toggle button on the front for RCA and XLR switching. After adjusting for the gain differences, I will be able compare with the LA4 preamp. Though I already know the answer. |
