DAC DIRECT IN TO AMPLIFIER OR TO PREAMPLIFIER

@lanx0003 

Although the average output impedance (OI) is rated at 300 and 600 ohms for SE and XLR line outputs, JA (Sterophile) pointed out that both SE and XLR OI can rise to 3150 and 3900 ohms at 20Hz. This necessitates an amplifier with at least a 40k input impedance to avoid bass sounding lean.

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.

@mitch2 I believe it was related to the size of the coupling caps used.

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.

I know a lot of folks do not care for this guy or his musings, but he has a point if you are digital only. https://youtu.be/81RQLo0tLHE?si=t9BKS9t34O0bESV2

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)..

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.

I had Canary Audio 300B Mono amps with a Canary 1800 Dual Preamp.  I had a Lampizator Pacific  DAC.  People kept telling me I should try the Pacific direct to the 300B's but I wouldn't.  Then one day, just for the hell of it I did try going DAC to Amps.  I was astonished.  I thought the sound direct was better.  I immediately sold my Preamp and for the next year was a happy camper.  Then I sold the Pacific and replaced it with the Lampi Horizon, which has an even better Pre.  There have been many debates on WBF with Lampi regarding pre or not to pre.  I would say it is 75% Pre to 25% direct to the amp.  

I am still running my system without a Pre but I now have Aries Cerat Ianus Essentia mono amps.  Although my music sounds great in my opinion, I decided to order an Aries Cerat Ianus Ageto Pre.  I am still not convinced my sound will be that much better, but I hope to be proven wrong when I do get the Ageto.