Three of the top DAC makers avoid this design choice entirely, and their reasoning is hard to argue with.
Ricardo Franassovici, founder of UK high-end audio distributor Absolute Sounds, says tube-based DACs are “boutique digital.” In his view, they are designed to sound like turntables rather than address the real challenges of digital audio.
From an engineering standpoint, much of the evidence supports his argument. However, the key question is where tubes sit in the signal chain and what they actually change.
What Franassovici Actually Said
Speaking at the Audio Show Deluxe 2026, Franassovici drew a clear line between what he considers genuine digital engineering and what he sees as aesthetic design choices.
His argument is not that tubes are flawed. Franassovici’s concern is that adding them to a DAC blurs the distinction between digital conversion and analog coloration. That distinction becomes central to his broader critique of how digital audio products are often positioned in the high-end market.
Franassovici has distributed dCS for years, which is a brand known for its engineering-focused approach to digital audio. And at dCS, the emphasis is on precision digital conversion and proprietary processing rather than analog-style output tuning.
His position reflects that background.
What Tubes Actually Do Inside a DAC
To evaluate that criticism, it helps to look at where tubes sit in the signal chain and what they change.
A DAC’s primary role is conversion. It takes digital data and reconstructs it as an analog electrical signal. This process involves filtering, noise shaping, and reconstruction. All of it happens before the signal reaches any tube stage.
Tubes are typically added to the analog output stage, after conversion is complete. At that point, they do not affect how the digital signal is decoded. They shape how the final analog signal sounds.
In practice, tube stages introduce even-order harmonic distortion, subtle compression, and gentle frequency shaping. These effects are often perceived as warmth or smoothness.
Plus, they are also commonly associated with vinyl playback, which is why tube DACs are described as more “analog-like.” And for certain listeners, that is a feature, not a bug.
Still, tubes do not improve the accuracy of digital conversion. Rather, they reinterpret the signal after the conversion has already taken place.
Even well-implemented designs can come with trade-offs inherent to how tube stages operate. They tend to raise output impedance, which can affect compatibility with certain amplifiers.
Moreover, tube stages can introduce additional noise and distortion. Some designs may exhibit a slight high-frequency roll-off, depending on implementation.
Bottom line, the qualities that make tube DACs sound warm can also be tied to measurable changes in the signal.
What Serious Digital Engineering Actually Demands
If tubes do not address the core challenges of DAC design, what does? The answer lies in where digital audio systems actually introduce error and how designers attempt to minimize it across the signal chain.
But engineering-focused DAC design typically prioritizes low-jitter clocking, advanced filtering algorithms, FPGA or DSP-based processing, and carefully designed power supplies.
dCS, for example, uses a proprietary Ring DAC architecture instead of standard off-the-shelf chips. Chord Electronics builds its DACs around FPGA platforms running custom code, with extremely high levels of oversampling. And MSB relies on discrete R2R ladder designs with tightly matched components.
In each case, the engineering focus is on the digital conversion process itself rather than post-conversion shaping, such as tube stages.
This supports Franassovici’s broader point that analog circuits can be tuned through component choices, but digital conversion is less forgiving because conversion errors cannot be voiced away.
The Price Premium Problem
Franassovici’s criticism becomes more pointed when applied to pricing. Tube-equipped DACs command higher prices. These products are usually marketed around qualities such as warmth, musicality, and a more “analog” presentation.
From an engineering perspective, those qualities come from deliberate changes in the analog output stage. They do not reflect improvements in the accuracy of digital conversion.
This shifts how the price premium should be understood. A tube DAC does not offer more precise decoding of digital audio. It offers a specific type of sound shaping layered on top of an already converted signal.
Franassovici’s description of “boutique digital” is deliberately provocative. Technically, his point holds. Tubes do not enhance digital conversion. They modify its output. Whether that matters depends on what the listener values more, accuracy or a particular sonic character.
The debate ultimately reflects two different definitions of “performance” in audio. One is rooted in fidelity, and the other in personal preference. As Franassovici highlights in another interview, “digital no longer needs to sound analog to sound good.”
Riccardo is right on! If you want to add tube warmth to an already-converted analog signal, use a tube line stage or output buffer. dCS gear is great but very expensive. I have used a Chord Qutest (with sBooster linear power supply) for years. The fact that it is still in production speaks volumes. (For 30 years, I wrote as Sam Tellig for Stereophile.)
Sam Telig wow. I bought my p25 because of your review. Thanks
I own a Cary 200 T/S which allows me to switch from tubes to solid state with a flick of a button on my remote so it is possible to hear the differences immediately. I have lots of AU7 tubes – all with their own sound from RCA Cleartops to Mullards with long plates and the difference in sound is quite dramatic BUT I usually forego the tubes altogether. Depending on how you like your music to sound it is an alternative especially if you have bright sounding speakers.