Is a Step-up Transformer needed?

Hi, I am using a Denon DL-103 with an Output Voltage of 0.3mV and a recommended load resistance of 100 Ohms or more except when transformer is provided (direct quote from instruction manual) and a Pro-Ject Tube Box SE which can be set to either 100 Ohm, 220 Ohm or 1kOhm. I am confused about the output voltage issue. Can I use any of these settings without the step-up transformer? Thanks.