The DAM-1's core is the Jinling DSP with its "cutting-edge" upsampling/filter functions, a dual phase-lock loop, FIFO buffer and claim of -170dB distortion at 32 bits. It can work in pure 1-bit native DSD mode, do PCM NOS, upsampled DSD256/PCM384 or resample all PCM to DSD256 on the fly. Finally SAW mode "auto-selects the optimal decoding method for lowest jitter". D/A conversion is dual mono. Another block diagram shows an 'enhanced D300Ref USB⇒I²S/DSD' module based on a new XMOS USB transceiver controlled by 22.57/24.57MHz reference clocks. The external PA1-Ref runs its own 12MHz OCXO. Clock specs are ±0.05ppm stability with -145dB of phase noise. Lo/hi gain on RCA means 1.7/2Vrms, 3.4/4Vrms on XLR.

According to official materials, across four years of R&D the DAM-1 underwent seven major revisions before reaching production. It measures 32x22x6cm WxDxH and weighs 4.3kg. Why did Soundaware opt against 768kHz PCM and DSD512 or even higher sample rates? It's because their super-cap output voltage won't support thirstier processors necessary for those higher rates. Cost considerations too voted against higher power-supply voltages or faster crystal oscillators whilst attempting to duplicate the current machine's excellent noise and accuracy parameters.

This display shows 'F1' for the first of four filters selectable only in 'normal' mode: 'L' for low gain; 'P' for positive polarity; mute disengaged; 'normal' mode at 352.8kHz upsampling; and the AES/EBU input selected. Now I asked Weng to explain the difference between PA1-Ref and LPX power supplies. "The LPX with super caps is specifically designed for listeners who only use the DAM-1 DAC. The PA1-REF with super caps is for users who also utilize the PA1 module for other DACs and which includes network regeneration not available in the DAM-1. So the PA1-REF offers more versatility."

Next I asked about the DAM-1's 'PA1 enable' button. Why would one pay for a performance enhancer only to defeat it? "The 'enhanced D300REF USB to I²S/DSD' module mentioned in the DAM-1 block diagram refers to a USB regeneration function which the D300Ref doesn't have. By engaging 'PA1 enable', we activate the internal regen module." With it active while a PA1-Ref not LPX/LP1 powers the DAM-1 and USB loops through the Ref, don't we put 2 x USB regenerators in series? That would mirror 'multi-mode' network users who slave two or more LAN switches in series. It took a number of emails between me and Weng before the penny dropped. "We don't recommend two PA1 USB Regen modules in series. While they may lower noise, they could also introduce latency and other side effects."

So the DAM-1's 'PA1 enable' switch is really for users whose PC/Mac or USB storage device sends signal to the DAM-1 without prior USB processing. When the PA1-Ref's own USB regenerator loop is used into a DAM-1, the latter's internal regeneration should defeat. We appreciate how the LPX is actually all we want for a DAM-1 super-cap supply. The PA1-Ref is for users of other DACs which don't include their own USB regeneration. It's just my review's overlap of DAM-1 and PA1-Ref that has any potential 'dual regen' scenario arise. Unlike LAN distributors where for top results SOtM promote three of theirs in series, Soundaware do not champion serial USB regeneration. To reiterate, DAM-1 buyers wanting the best power supply will get the LPX then exploit the DAC's internal USB regenerator. Owners of other DACs who want a USB bridge to isolate DAC from PC/Mac will pursue a super-capped PA1-Ref to loop their USB feed through it. Now only Soundaware's auxiliary 4-pin power socket goes unused. For my review, I'd use the PA1-Ref like an LPX so super-cap power source for the DAM-1. A single USB cable would enter the DAC's internal USB regenerator. To review the PA1-Ref by itself, I'd use it as standalone USB bridge with any of my resident converters. With all my coordinates crystal, I had my marching orders. DAM-1 shoppers thus have two choices: a €3'649 bundle with LP1; or €4'989 with LPX. Don't spend €5'898 on a PA1-Ref combo. That's only for those few who first bought a Ref then later decided to upgrade an existing DAC to DAM-1. Now that's available at €3'149 without PSU. Options. They're lovely to have; but can be confusing at times.

One final PA1-Ref factoid. Unlike my D300Ref, it's no DDC. It doesn't convert USB to coax/BNC, AES/EBU, Toslink or I²S. It's USB in/out. Why is that relevant? Because it cancels S/PDIF's 192kHz limit, even dual AES/EBU's 384kHz. Should we wish, we may send up to 1'536kHz signal from Mac/PC to DAC via the PA-1Ref's reclocker. That will be Redbook to native DXD files which player software like Audirvana's r8brain/SoX engines upsample. Whenever we send a DAC the max sample rate it can process, we automatically bypass its own upsampler. Is it better to upsample in PC/Mac or DAC? I've heard arguments for both. Favoring a proper computer are the far greater processing resources it can apply to the task than an FPGA. Favoring a DAC are claims that higher sample rates sent down a digital cable increase the potential for induced jitter. As always, our own ears must decide. In my two computer-fronted systems, I split the difference. Audirvana's r8brain upsampler is set to always generate a 176.4/192kHz output. Various DACs then add their own upsampling; or not. The sonically most relevant lifting has already been done. "We adopt a FIFO plus asynchronous sample rate converter to reduce the external clock requirement and use our local high-performance clock instead. The main difference between NOS and normal modes is NOS being least affected by the filter and oversampling at low sample rates and transient distortion being significantly lower. Normal mode uses the Sigma-delta method of our classic flagship chip."

Whilst the remote has vol ± buttons, according to the above superimposed graphic they still remain unassigned just like the Fn button. So no volume control on the DAM-1. Really? The owner's manual, under explaining the front panel buttons, had this for the 'filter' control: "Filter mode selection only available in normal mode, F1-4, long press in NOS mode for volume preamp on/off."  As it turns out, there is remote-controlled volume from -60dB to 0.0dB.