A constant source of debate for audio professionals and musicians is analog vs digital. The fact is most digital devices have analog components within. A sound card converts the digital PCM data stream into an analog signal and it passes through and analog amplifier en route to the outputs (and vice versa). Much of the debate has been fuelled by the perception that analog sounds warm and digital sounds cold. This is a subjective issue and ‘warmth’ means different things to different people. Historically sound studios employed all analog equipment such as mixing consoles, tape machines and high quality outboard equipment such as compressors and equalizers.
The introduction of digital started with recording devices, DASH multi track and DAT machines appeared as recording mediums. Initially these devices had a tendency to sound quite clinical because they did not have the saturation and top end roll off that analog tape exhibited. It has to be said that digital recorders today still have a linear response in the high frequencies which could account for part of the perception of digital being cold sounding.
However digital has come a long way since the first generation of AD and DA converters and the fidelity is much improved. I believe that whilst analog equipment has desirable traits ’ warmth’ is not something to get overly hung up on. There is a large number of software plug ins that emulate classic recording equipment so musicians have the chance to own a similar sounding emulation for a few hundred dollars. My personal belief is that many aspects of the recording industry have changed that also account for a sonic difference. Professional engineers were trained for hours as assistants and this skill and knowledge cannot go without credit. This in itself plays a huge part in achieving quality sounds at source from the very moments a microphone is placed in front of a musician and instrument. I believe tape has a significant impact in warm sounds as well, I think there is a split between wanting both the clarity offered by digital recording and yet a yearning for warmth as well. The bottom line is normally one has to be sacrificed to a degree to accommodate the other and this is where acuity of hearing becomes important because there is a fine line between the 2.
To generalize, if I was to apply a low pass filter across a mix and nothing else at around 10kHz I think most people would suggest this mix had a ‘warmer’ sound to it, whereas you could pass the mix through a series of analog kit without such a filter and many would not know the difference. So application of digital tools can in fact assist in achieving a warm sound. With that said there are certain pieces of analog equipment which have a pass through character which can natural subdue the highs and also widen the sound stage a little so analog equipment is certainly far from redundant.
The overall message is not to get overly hung up on expensive analog equipment because it has never been as good for musicians and engineers inside their digital audio workstations. I suggest if you feel a mix down is lacking warmth to step back and try and understand why, what elements of the mix are causing it to sound cold or harsh ? Start with EQ and try and gently carve the sound and leave some listening time in between. You might surprise yourself how far you can get with judicious processing carefully applied.