Dumb question......why do you need a preamp?

Having enough output voltage from a source component to drive the amplifier(s) is a good start, but may not be enough for some listeners depending on their equipment, set-up configuration, and listening preferences. Listeners who use passive volume controls, either inside or outside of the DAC, typically value the clarity and absence of noise they perceive from removing the active stage from their signal path. However, even with source components having enough voltage to drive the amplifiers, impedance differences between source and amplifier, and cable length, can affect the sound. Improved dynamics, body, and tonal qualities are what I read about most from folks who switch from using passive volume controls to an active stage, or a transformer/autoformer based solution.

Of course, active circuitry and transformers add their own sonic changes (and potentially noise) to the signal so, the trade-offs are sometimes described as improved clarity and lower noise when using a passive solution vs. improved body and energy when using active circuitry.  Choices include either:

• Live with the impedance relationship between the source component (usually a DAC) and the amplifier(s) and minimize the effects of impedance by keeping IC cables short and selecting equipment with low output impedance and high input impedance, or
• Utilize an active stage (or transformers/autoformers) between the source and amplifier(s) in order to improve the output/input impedance relationship.

In cases where the source output voltage is sufficient, the active stage can be as simple as a unity-gain buffer (you would not need more gain), or transformers/autoformers, which can be set up for unity or other levels of gain up to about 6dB. Examples include totaldac’s d1-driver-sublime, which I believe is basically a low (or unity) gain active stage, or Empirical Audio’s Final Drive, which are a pair of passive transformer buffers/selectors. In both examples, the manufacturer’s goal was to insert a device in-line that optimizes impedance matching in order to improve the sound of their DAC when directly driving amplifier(s).

Simple answer, it sounds better. I have a Ayre KX-5 Twenty, it wasn’t cheap. I tried the bypass from my CD player straight to the DAC as I have a volume control on the CD player. It sounded lifeless. There’s a reason the preamp is one of the most expensive components in a system and one of the most important. I can’t get over how much I’d been missing before I got the Ayre preamp.

I’m a true believer if you want a top sounding system, get the best preamp you can afford.

I run a 'vintage' audio system (so, equipment from the 1960s / 1970s; and things like a Reel to Reel tape deck, etc.) and I recently switched from a fully integrated solid state receiver (which is basically a tuner / preamp / amplifier all in one unit) to a tube preamp / dual solid state monoblock amplifiers.

In all fairness, the receiver I had was a very good high output unit for it's time (160 wpc) and the sound quality was also very good... I have noticed, however, what I feel is an improvement in overall SQ with the separates setup; and more specifically, adding tubes in at the preamp stage adds a certain quality and fullness to the sound that I did not even know was 'lacking' in my previous configuration.

I thought perhaps it was simply confirmation bias on my part; but I have gotten similar comments from my family members that they too hear a pleasant difference since my 'upgrade'...

With an integrated amplifier you do not need to use a preamp, but there may be reasons you might want to. If your integrated amplifier does not have a built in Phono section is one reason off the top of my mind to add a preamp.

All the best.

Two reasons to “need” a pre-amp

1) to deliver a particular sound that you like 

2) features that may be useful. A volume control would be most common.  
 

If you already have these then you do not need a preamp.