sound_forward, I'm exactly like you, since I bought my RME Fireface 800 I have missed my simple and cheap analog noisy tape recorder. But let me tell you about my view on this.
I first thought it was my Fireface that was killing all the tone, but I was wrong. The Fireface is just fine, an excellent peace of gear. The problem with it is that it translates the tone so close the original that you get dissapointed by the fact that you are used to warm sounding recordings and all of a sudden it's just 100% exact and lifeless. I learned that I should not blame my converter for this, it does exactly what it is supposed to, it might not be the best for great imaging and dynamics, but it doesn't kill any warmth and it is good sounding. Now you go, AND... get to the point...! I will. First of all there has to be warmth in the tone in the first place, that means your sound source must be rather soft sounding. You can try to make harsh sounding instruments soft sounding, but it will be a little noisy anyway because the modifying frequencies are adding noise, the sum of this is lost overall gain on the recording and when compensated with a limiter the softness that once was there will be gone. So the first step is to select soft sounding sound sources. If you don't have that opportunity the best thing you can do is to do what you can do with your gear. First of all choose a soft sounding combination of pre amplifier and microphone(s). Forget that if you can't afford it. BUT here comes my point: Softness comes from compressors. It doesn't come from reverbs, it doesn't come from chorus etc. It comes from compressors! Focus on the compressors when you want warmth, no matter what converter you use you will want to get as much softness as possible in the end and the single most effective effect that adds warmth in a recording is the compressor effect.
To compete with the professional recordings of today is hard, the reason is not only the quality of the sound sources and converters, it's the sum of the quality of the compressors used in the recording as well. You might think, but I have a bunch of compressors and it doesn't work at all. Two things: Choose a warm sounding compressor, set it up correctly! Have you tried increasing the output of the compressor to a surprisingly high value? Try that, if you are not satisfied with the softness in your current compressor. Record as low as you need for the compressor to add as much warmth as you need, also use the attack. Tweak a little. When you get that softness, increase some mids and highs too (after the compressor) so that the listener doesn't end up with a headache. Don't leave the mastering engineer with too much power. If he doesn't have a warm sounding limiter, choose another mastering engineer. Mastering engineers are typically good at increasing the loudness, but often the result is even less warm. A good mastering engineer should be able to increase the amplitude without killing warmth, it is not possible with a harsh sounding compressor/limiter and it's the mastering engineer's responsibility to have knowledge about what limiter to use. For instance, you might be familiar with the Waves L2 limiter. It's a warmth killer! Leave it alone! Try increasing the volume instead of limiting hard and then compare that with a hard limited L2 version and you will notice that one is soft and the other is hard sounding. This is a very typical mistake, the sound source is soft, the pres and mics are soft, even the compressors during the production are soft and then comes a dead cold limiter in the end that also is over-applied, ruining the whole recording!
So I recommend that you study compressors a little more. Some people are so excited about their compressor that they even sleep with it...!
Best regards,
Andy