I want to start by paying tribute to those that care about safety. Making sure that the meter has fuses and protection and will keep me safe when I probe around in that electrical substation is genuinely a good thing. Only I don't have an electrical substation nor three-phase at my house. I can't even remember the last time I measured mains voltage. I know that these things matter even when you are on the far side of the transformer, but even that is rare for me.
What I measure predominantly are small ac voltage signals and it is here that multimeters are pretty useless. What may surprise people more, is that even the expensive high-performance models are poor at small-signal ac measurements. Not all of them, but most.
Yet, I cannot remember reading or watching a review that took a look at small-signal ac measurements. I'm sure there are some, but they are far from the norm. We get loads of detail on the high-voltage, high-current side of things and that is great alongside lots of attention to dc accuracy, but ac precision and how useful a meter is for small signal work is regularly omitted altogether. What we all need to do is to balance our coverage of multimeters by mentioning the higher bandwidth and lower voltage signals alongside the bigger signals and dc performances we cover now.
Accuracy
Its not uncommon to find that a very expensive high-precision bench multimeter reading dc to better than 0.03% has an accuracy of worse than 1% for ac voltages. A much prized 6.5 digit meter may well perform significantly worse than another much cheaper device with only 4.5 digits. It is very hard to find meters even amongst the elite that prioritise ac accuracy. The poor ac accuracy performance is missed in so many reviews so we should make a point of discussing ac accuracy and especially for small signals..
Range
When it comes to small signals, the situation is made even worse because of the lack of low-level ranges. Meters that have a dc millivolt range or even stray into microvolts sometimes start 5, 10 or even 30 times this for ac signals. This disparity is rarely mentioned and we really should. The combination of poor accuracy and the absence of low measurement ranges interact to make many meters singularly useless for small signal measurement, yet we almost never say.
Bandwidth
It is rare to find a meter that will handle the full audio bandwidth which is what I am most interested in. Meters often retain their accuracy only in the tens of Hertz or hundreds of Hertz. There are meters that are good for this, and this is one area where paying more often helps, but you have to look for them and you can't take it for granted. Again, this shortcoming is rarely mentioned in our reviews. While audio is what matters to me, people working on servo systems and dc motor drives as well as all sorts of sensor and drive circuits need wider bandwidths, in some cases way beyond the audio range I'm looking for. I am amazed that ac accuracy, ac ranges and ac bandwidth are not standard talking points in every multimeter review.
RMS
I am often shocked at people talking about the RMS capability of a multimeter without mentioning bandwidth. People will recommend looking for RMS capability for use with audio for example. Why do they do this? In most cases the meter does not cover the audio range and so whether it measures true RMS or not is irrelevant. Secondly, true RMS is unnecessary when measuring things like gain and line-up levels using tone. Keep in mind that meters are always less accurate when measuring true RMS, so where the meter has a choice, you are generally better off turning this function off. Where RMS is at its most useful is when measuring noise, but yet few multimeters have the range to usefully measure noise in audio equipment (or servo systems for that matter). If they could, fewer still have A-weighting which you may well need at some point, for sound at least. We make far too much fuss about RMS and rarely explain how limited its use really is. How many multimeter reviews have you read where the author never draws attention to the limited bandwidth?
Decibels
The ability to present the reading in dB is often scored well in reviews when in practice, I find that it is rarely useful. If you want to line a piece of equipment up, then you can convert from dB first and simply measure in volts. Where direct reading of decibels does become useful is when tracking changing values and most multimeters are too slow for their dB reading displays to be relevant.
Please throw rocks at my thinking here. Tell me I'm wrong. Point out that all this stuff is regularly covered. Happy to be shown to be incorrect on this if I am.
From your writing, I would gather you need to measure voltage in audio range. Probably for audio amplifiers stuff.
What you need is probably specialty low voltage AC voltmeter.
There are many articles and reviews that mention small AC measurements.
I would be curious to know what application needs better than 0.06% accuracy in audio range at levels of 10 µV RMS.
Accuracy: It depends on your definition of "high-precision bench multimeter". Even my "not very fancy" Rigol DM3068 (6 1/2 digit meter) has 0,06% accuracy on AC range (10Hz-20kHz) on 200 mV range. Simillary from Siglent and oodles of others. Also 5 1/2 digit meters from Siglent and Rigol will do 0.2% in audio range... TTi 1908 will too.. and bunch of others..
Range: There are meters (like I said, those are specific instruments) that have sensitivity you need. Standard multimeters with their unshielded banana connectors and probes are not fit for this purpose. You need coaxial, shielded inputs and probes for this. Maybe differential, even...
BW: I have 3 multimeters that have way more than audio BW: DM3068 (300kHz), MTX3293 (200kHz) and BM869S (100kHz). There are very many meters that have very wide BW.
dB: dB measurements are simple recalculation. On well implemented meter you can specify load impedance and get direct dBm reading. Speed will be defined by meter AC measurement speed. On DM3068 (for instance) i can specify AC RMS filter and in fastest setting, I get maybe 10 measurements per second. Enable dBm and voila.... Realtime response.
But you are correct. Most multimeters are not audio meters. Audio meters are specialized instruments, which multimeters are not.
To add, I also have a 16 Bit picoscope that is best AC voltmeter you can buy. 5MHz BW, scope, meter, and several dozens of measurements, spectrum etc...
People also use audio analysers for accurate level measurements.
If you want a simple and inexpensive solution, a preamplifier and decent meter does a good job too.
Or shall we take this question and set it differently?
How about you lay out what problem you need fixed ( "I need to measure this and this within these and these parameters and constraints. What you guys can recommend?") and I'm sure some solution will come out of it...